Advice on how to talk with crushes?

This guy that i like i really like him. Every time i see him i get the urge to giggle its really weird because hes really cute. Hes now a junior and im a sophomore and it sucks becuase we cant talk in class. i added him on facebook but he hasn't said anything .. or have i. i don't know how to start a convo with him because i don't even know if he knows that i exist, sure he probably has seen me in school but i like him a lot and i don't want to seem like a creep just talking to him on FB. Its really hard. Hes on the track team i'd join but i cant run for my life. God do i wish i was a junior now. I cant talk to him during breaks because i don't know where he might be lol. PLus im really shy. LOL! HELP!