First of all, I congratulate you on seeing some of the strengths of RPGs for youngsters.
Folks have already suggested a number of good things - your Friendly Local Gaming Store, the Gamers Seeking Gamers forum here on EN World, other online forums (like RPG.net)...
There's also play-by-post games running on these boards (in the Talking the Talk and Playing the Game forums). They don't have all the social contact of a face to face game, but many of the good and useful qualites of RPGs are still present.
Also, there's a chatroom associated with tehse message boards. At the top of this page there's a little dropdown menu labelled "Chat". Using that will run the java chat client and take you to EN World's Chatroom, where one can often get hooked up with games running in chatrooms. Again, not all the good stuff found in a face to face game, but better than nothing.
(Or, if you are familiar with IRC, point your favorite client at chat.psionics.net, ports 6660-6669, #dnd3e).
Oh, and I almost forgot - if nothing else, you can simply get some of your own friends together to try it. In your age group that might not be the easiest thing in the world, but it can be worth a shot, especialy if you can nose about your workplace and see if anyone else has ever played or wanted to. Learning the ropes is easier if someone else teaches you, but with the books, and a place like this to ask questions, you can manage on your own
