Glad you came. Welcome and Congrats. Well now that you're rooted you want to try out some sick Roms and you came to the right place.
I would say the first thing you should do is download Rom Manager. Its free and its in the Market. Once you have that, everything is a breeze. In Rom Manager they have the latest and greatest Roms available. Just click and download the Rom you would like to run. Most Roms have included themes and many options. A screenshot will show you what you're getting. Once you're done it will prompt you to reboot but first it will ask you if you would like to wipe cache and/or backup existing Rom. It is my opinion to always do both for two reasons. You wipe date and cache to get rid of any files from the previous Rom that may tamper with the new one and cause it to behave awkwardly. And always perform a backup in the event that something goes wrong doing the reboot process I.e. boot loops. If you perform a backup and you easily perform a restore that will take you to the previous image and get rid of all your worries.
Now lets talk about this thread. This thread gives you the extra Roms that don't make it to Rom Manager. Most Roms from Rom Manager make it here as well but we include the source of the download so you can follow changelogs, updates, more screenshots, and reviews. More importantly its to credit the creator. Downloading Roms from here require a 1 or 2 extra steps but I ensure you that its even easier than the root process itself (thanks to Rom Manager). I can help you with this =)
If you plan on downloading from your computer here you go: download the name of the Rom you would like to use. Connect your phone to your computer so that you may place this downloaded zip file onto your SD card. You can put it anywhere as long as you remember where it is. Once done, disconnect and your phone and load up Rom Manager. In Rom Manager select Install Rom From SD Card. There navigate through your SD Card, find and select your file. It will then prompt to reboot and ask if you would like to wipe and/or backup. From there, Rom Manager does its thing!
The other option is to download from your phone. Again, simply download the file from this thread directly from your phone. The zip file will go into a folder named Download. Once done, enter Rom Manager and again select Install Rom From SD Card. Open the download folder, find your Rom and boom. Same thing over again.
And that's it. There are other ways to download and install Roms but these two ways are the easiest. If you would like to know the other ways just ask and I will gladly help. If I can't help you I'm sure one of the other knowledgeable members that post regularly in this thread can help you.
Again welcome and Congrats on your successful root.
Edit: One last thing, I would also like to recommend an app called Titanium Backup. There is a free and paid version of the app. The paid version will help you backup and restore your Apps easily after performing a data wipe. There are other alternatives out there but again, I'm just trying to simplify things for you. If you're interested and need a tutorial for that as well, just let me know.