Step one: Consolidate forums. Lump TV, games, music, and movies into a media forum. Consolidate all talk-about-yourself and suggestion forums into one General Discussion forum.
Step one-and-a-half: Hide the evidence: Delete this post.
Step two: Subjugate all your friends into using the forum at least once a day for as long as you can. 2 weeks should do the trick. That will get the ball rolling as a sense of community is quickly built.
Step three: Moderation: Don't install any moderators, or at least not more than one. Your moderator should know to be impartial and only moderate posts that could cause lasting damage (suspension from school, firing, public ridicule, etc). So basically, tell people to clearly mark NSFW stuff as such. Having moderators, particularly more than one (on a teenage forum) makes it appear you are playing favorites.
Step four: Growth. If you succeed in making a successful forum, the odds are high that you will quickly outgrow your alotted sever capacity and you'll have to move to a dedicated server which costs about $100/mo. Time to pass the collection plate.
If you couldn't tell, it's 1 AM and I'm bored. Thanks for the gift. Actually, I hate Pho. Maybe I'll give you a gift in return anyway.