Desperately need help! I don't know what to do about this guy?

Well to be honest from what you have said it sounds like he likes you, you should try as hard as you can to smile back at him when he smiles at you and when you walk past him say hi, if you have facebook add him and talk to him , its much easier to talk to people over email, or you could just go up to him in school and start chatting, because it sounds like hes worth it :)