*blush* xD D'aaw...wow, thanks! Heh heh, I drew/colored the banner and art stuffs around the site. :3
Anyhoo! Welcome, Beth! 8D Hope you have fun here!
As for creating new species and stuff, you're free to do that all you like, there really aren't any rules. You just, well, do it! xD You don't have to submit your race creations to the site, either, but if you've written up a lot of information about them and would like other players to be able to play as them, then you can submit your idea. :3 It's not mandatory, though!