For the organization of all games being played on these boards (the ones in Playing the Game), there's a specific section for that. It's called Talking the Talk. This is where all the games are being started, and where all of the Out-of-Character (OOC) conversation takes place.
If you play a game, check that forum. If you want to play, check the ones that say [Recruitment] in the subject. They pop up quite regularly. Also, you might want to make a thread that says you're a player looking for a game. DM's usually respond to that with offering you a spot in upcoming games.
If you want to run a game as a DM, just start your own thread with the [Recruitment] tag in the subject. Give some guidelines for what kind of game you'd like to run in the body, such as game system, genre, level, amount of players, etc. Just go with what you'd like to do, or you could check other such threads to see how the application is normally done.
I hope that's enough information for you. Feel free to drop by in the Talking the Talk forum. That's where all of this is going in, and people will be able to help you with any and all questions (related to gaming here.) Welcome and I hope you enjoy your stay.
Fanog