Ooh, tough. You have to choose between three guys.
Well, for the first guy, try to talk to him more. Make conversation, get closer to him, smile often, and when the time is right, ask for his number/add him on facebook/that sort of thing. Keep in touch with him often, send him funny forwards, and just talk to him a lot, and then suggest that you guys hang out more. Slowly work your way up.
As for the second guy, if you don't know how you feel about it, you don't need to rush into anything.
And finally, the third one, it's pretty obvious that he likes you, albeit he shows it in an immature way... it's up to you, I guess. Personally, if I were you, I'd go after the guy I like first. If nothing happens between you two, it's not the end of the world, and you have other boys to try. Not that you should be selfish and give top priority to "the best" guys, but if you have genuine feelings for someone, and you really want to give them a chance, I'd start there first.