I'm in love with him and he doesn't know?

Are you sure you like him? Hang out when you can. If and when you do, get to know him a lot more than you do now. If you really like him, tell him how you feel. If he doesn't feel the same way, forget about it and stay friends, if possible. If he does like you, but he's too shy to ask you out, then ask him out yourself. There's nothing wrong with asking a guy out.