If you've been going online & playing, I assume you have the basic understanding of game rules. That should be all you need to play poker with the guys. However, if you mean you wanna know how to play poker WELL, that's a whole different matter. Poker is a game with so many theoretical paradoxes about when to bet & fold, that just telling you a bunch of information wouldn't help. Just get out there, play, lose, & get better. That's the only way it can happen.
I guess one piece of advice I could give to a beginner is hold back. If you don't think you can win, fold. If the raise is more than you can afford to lose, fold. Good players love to get noobs playing a game of chicken with them and taking them for all they've got. As you get better, you can become a more & more aggressive player, but make sure you master self-restraint first. Do this and you'll allready be better than the majority of poker players out there.