Heya CK, there are plenty of games constantly advertising in the Games and Ads
section of the forums. Many of the GMs/DMs are only too happy to help you learn how to play.
There are, of course, different editions of D&D. I myself tend to focus on AD&D and 2nd Edition, while others play 3.0, 3.5, 4th, and I believe there is play testing of D&D Next (5th Edition) going on at varying times. Even still, there are OTHER games people play on here as well, ranging from the primitive to the futuristic, from the oldest of rules sets to the very newest. Don't limit yourself!
As far as your 1st level psionicist, your enthusiasm is welcomed! However, that psionicist may not even fit in many games that are running here, and most DMs/GMs have people roll up characters within their own game threads. Myth-Weavers does a pretty nifty job of handling things like dice rolls so that they are fair and make for fair play.
Don't let any of this discourage you though! Look around in the Games and Ads section, find a game that catches your fancy, and jump on in!