There are many post explaining what your asking and your right there are some members that write up very detailed answers but I'm not one of them but I'll give er a go. Changing roms are so easy. In fact some of us do it on a regular basis. I personally do it without using my computer and that's how I will explain it. Then if you get stuck and need to do it the other way let us know.

1. Using the browser on you phone, choose the rom you want to download. Since you are already rooted with a custom rom I will assume you know where and how to get them.

2. My personal favorite is Condemned Souls CM7. Condemned Soul (The Dev) is also very active in the forums and is very helpfull with questions concerning his rom.

3. Also make sure if there's anything else you need make sure you download that as well. (some require that you flash gapps after flashing the rom) (gapps is the google market)

4. After download/s are complete, go into your file manager (Astro or I/O) and the zips you downloaded will be in the download folder.

5. Long press the file/s and select move. At the top bar you'll see the sd card icon, select that then click the bar that says move. After you've done that close file manager and then open it back up. When you open file manager it defaults to the root of the sd card. Look to make sure the files you moved are there.

5. Also check to make sure your md5 sums are the same using Scary Alein's AFV app.

6. Boot into recovery and do a backup of the current rom you're using. Then do a full wipe. (wipe data/factory reset)

7. Flash the rom, then flash gapps (if the rom your flashing needs it).

8. Reboot

9. Wha la there you go.

10. You won't lose you paid apps. You can backup your apps with TiB. Just remember do not backup System Data.

 

The md5 sums are found on the dev's thread. He will post this for his rom. I still don't know how post a link from my phone but if you look at thread Scotty started for condemned souls rom and read down a few post you will see that he posted the md5 for his rom. There is a thread called AFV (android file verifier) by Scary Alein. I made a post on it this morning. His app which is free in the market (although a donation never hurts cause those guys work real hard to make these things for us) is among a lot of other things will check the MD sum to make sure what you downloaded is the same as what was published. Also he will explain it much better than I can. Flashing a rom means installing it. Every body here is very helpful. Hope that helps

 

Also I personally don't check MD sums. BUT I DON'T CONDONE IT. I take a chance but what I will do is check the megabytes of what I downloaded against what is published. Their are others that would scold me for some of the ways I do things but that's me. I'm a bad bad plumber.

 

What?!? (scary alien is aghast! )

BC, by the way, if you truly do have a signed .zip file (like a custom ROM), you can verify it's integrity and completness with my app without specifically knowing or having to lookup / compare the MD5 sum. You do this with the "Verify Jar-type File" option in AFV.

Amon_RA recovery won't let you flash a .zip file that has a bad/incorrect signature, but ClockworkMOD will (unless you enable that feature--seems like I also heard that they (Koush) has turned that on by default in more recent released of CWM?, but I don't know that for sure--not a CWM guy at the moment).

Cheers and thanks!

 

Just to help a little bit, this is what I do.

In order to run most of the Gingerbread ROMs now out there, you need to flash (perhaps a synonym that is easy to understand is "install") both the zip file that contains the Gingerbread ROM itself, as well as a zip file that contains some core Google apps (mostly the Market app, but a few others as well.) Note that this is not the case for two ROMs that I know of - the latest GSB ROM does not require a flash of the Google apps (because, presumably, those apps are already in the base ROM). The second is a beta version of a port of a Sense-based Gingerbread ROM that also includes the Google apps. Note, however, that this ROM is not yet 100% feature-complete.

Ok, that said, you have to choose the Gingerbread ROM that you want to install. The only one that I would definitely stay away from is one called KaosGingerbread, which is not feature-complete and seems to be abandoned by the developers. GSB, Gin-Tazz, CondemnedSoul - all of these are good GB builds. I'll put links to each at the end of the post.

You need to download the zip file to your SD card, just as you did when you installed Nonsensikal. You can download using a PC and transfer the file over, or you can do as Bobcat recommends and download using the phone's browser. I find that more unreliable, plus I like to save my phone's battery for actual phone stuff, but either way is fine. Just get that file (plus the Google apps download, if the ROM you are installing requires it) onto your SD card.

Then you will follow this procedure:

- Restart the phone in Recovery. Presumably you have done this before, but usually you power down the phone and power up while holding the VolUp key. If this does not work, you can power up using the VolDn key to start in what is called HBOOT mode and you should see a prompt to start recovery by pressing VolUp. Do that and you will start the Recovery image, which should present you with a text menu with green characters on a black background.

- Go to the Backup/Restore menu

- Choose the option "Nandroid backup". You will want this if something goes wrong and you want to go back to what you have now; follow the same instructions up to this point and choose Nandroid Restore to get a menu to bring you to the restore point that this will create if you ever do need to go back.

- When the backup is done, press VolDn to go back to the main menu

- Go to the wipe menu

- Choose "Wipe data/factory reset"

- Choose "Wipe Dalvik cache"

- Press VolDn to go back to the main menu

- Go to the "Flash a zip" menu

- Find the zip file for the GB ROM that you wish to install (this is the "flashing" step)

- if you need to flash Google apps as well, go back to the "Flash a zip" menu and choose the Google apps zip file

- Choose the "Restart" menu

And, as long as you had no errors while flashing the zip files, this will restart your phone and bring you to the initial setup for the GB ROM that you chose to install.

Links:

[ROM][5/23/2011] GSB v3.4 ODEX | GingerBread 2.3.4 [CM-7.1.0 RC0 NIGHTLY] - xda-developers
[ROM] 5/22/11 Condemned CM7 V8, GRE (5/13/2011) post 2 & Stripped version (5/22/2011) - xda-developers
Ginger Tazz 27 s.r.e 5/11.11/ CM 7.1 --2.3.4 - xda-developers

and that Sense one (do not use this as an everyday ROM, unless you are ok with no Bluetooth and a little bit of lag): (WIP) Gin-Sen-Tazz beta-6-5/25/11-GINGER SENSE - xda-developers

 

See I told you were other's that explain things so much better.
And by the way I use stripped2hell.

 

The last time that I turned on signed file verification in Clockwork it would not install a zip file that I knew was fine (because it would install from Amon_RA just fine, and, of course, passed the test in AFV.) I should note, though, that I haven't tried this in Clockwork in a couple of months. The next time that I flash a ROM I will, though.

 

I would like to ask another question which is a little off topic but kind of pertains to this. What about Rom Manager? Do I really need it, what is its purpose?

 

I think that it's safe to say that, on the Eris, you do not need it at all.

ROM Manager is a front-end application to another recovery image for Android called "Clockwork Recovery". For many phones, ROM Manager/Clockwork has one great feature - you can completely automate the installation of CyanogenMod ROM images for your device. While there is now support for the Eris in CM, I do not believe that you can install the latest stable or nightly images of CyanogenMod (the nightlies are the latest alpha and beta versions of CyanogenMod) as you can with a phone with official CM support, such as The Droid Incredible or the Sprint Hero.

However, ROM Manager/Clockwork do have some good features. You can automate the backup (or restore) of Nandroid images right from the ROM you are running without having to manually start Recovery and do the process steps yourself. Id you do start Clockwork Recovery, I do prefer its Wipe data feature over Amon_RA recovery, since it will also wipe the .android_secure folder on your SD card (where Froyo and GB builds store apps that are moved to the SD Card), as well as any ext partitions on your SD card, where many 2.1 based ROMs store applications that you move to SD. That way, if you flip between two different CynaogenMod builds, you will not have any apps that you store on SD get picked up by the new ROM - I am not 100% sure, but there may be a slight difference between the way Froyo and GB ROMs store apps in .android_secure.

One other plus is that the Nandroid backup and restore in Clockwork backs up those .android_secure folders and ext partitions on the SD card, if you have them. That way you are 100% sure that any apps that you may have moved to SD on a particular ROM will be restored if you like to flip between different ROMs.

Ok, all of that said - I generally suggest that you stick with Amon_RA recovery.

 

Like Scotty and of course thanks to Him I have Amon's recovery on my Incredible. I used clockwork at first but Mr Scotty led down the right path and showed me the way. I couldn't flash Amon's recovery in clockwork for some reason and ended up doing it thru hboot. I'm much more comfortable with Amon. FWIW.

 

Restoring system data is not a bad thing if stay with the same rom. If you switch to a different rom do NOT restore system data. You can backup apps as many times as you want to in TiB. It will write over the previous backup (I believe) tho one of the other fella's may clarify that.