Home screen - Any of the multiple "pages" that you slide across. Think of it like your Windows Desktop. On these home screens are your widgets and your app icons. You can add and remove home screens by pinching the screen. When you do that a preview of all your home screens pops up. I'm sure you can figure it out from there.

Apps - Programs that you launch from the application drawer or by pressing the icon on one of your home screens. They only appear as icons, and when you press them they often open full screen. For example the browser is an app, as are any games.

Widget - A widget is an interactive tool that sits on a home screen. It is different from an app in that it doesn't need to be launched and won't take over your whole phone when you use it. To see a widget long-press (press and hold) a blank space on an empty home screen. When the menu pops up select widgets and select something from the list. I like Samsungs Feeds and Updates widget. Select that and log in to your FB or Twitter with it. The Google Search bar that I think is applied by default on the Charge is a widget.

Installing a new launcher - The first thing you need to do is clear all of your original home screens. So pinch the screen and close each one until you only have 1 home screen left. Once that's done you need to clear any widgets or icons off of your last home screen. You're doing this because some people report that even when you use a new launcher your old launcher is still running resources in the background. Closing everything will reduce the memory usage and improve performance.

Now you need to find yourself a launcher. I recommend go launcher EX. It's free and IME it's the best one I've tried. So hit up the market and download that. Once it's done downloading and installing all you need to do is hit your "Home" button. The one that looks like a little house. Now it will give you the option to choose what launcher you want to use. Select Go Launcher and click the "Use by default" option. You will now launch into Go Launcher instead of Touchwiz and enjoy much improved versatility and performance.

What if you don't like Go Launcher - That's OK! It's easy enough to go back to touchwiz. Hit the menu button when you're on any home screen and go to settings > Application Settings > Manage Applications > and find Go Launcher. Press the "reset defaults" button and then press the home button and you'll have the option to choose Go Launcher or Touchwiz. Select Touchwiz then head back into Manage Applications and uninstall Go Launcher.

 

I used Open Home on my Droid 2 but I haven't tried another launcher on my
Droid Charge.