My LG Is Poop: I'm glad to hear that the guide worked for you... mostly anyway. The custom ROMs that I've tried had the Google Apps (GAPPS), including the Play Store, built-in, so my guide was based on my experience with those ROMs. However, in looking at the thread for the Kraven CM7 ROM that you downloaded, I see that, in the section #3 of Kraven's original post
(under "Google Apps") it says that it is required
that you also download Google apps (GAPPS) and flash them onto your custom ROM. Apparently Kraven feels that it's better to keep the GAPPS separate from his ROM so that they can be updated independently. (I've now edited my guide to account for that.) You'll need to:
1) Download GAPPS to your PC. (You can see section #3 of Kraven's post, but the latest version of GAPPS posted by Kraven is HERE
2) Connect your phone to your PC via USB, turn on the USB storage, and move the GAPPS zip file to the top level of your SD card.
3) Turn off USB storage and reboot into recovery mode (as described in step 5B above.)
4) From the Xonia custom recovery, select "Install zip from sdcard".
5) Select "toggle signature verification" to make it "Disabled".
6) Select "choose zip from sdcard". Select the GAPPS zip that you downloaded, apply it, and confirm.
7) From the Xonia main menu, select "reboot system now".
Your phone will reboot and you should have Google apps like "Play Store". Then you can resume from step #9 above in my original post. Sorry for the inconvenience.