How do I ask a Guy out?

I am 12 years old (just so you know). There is this guy I like at school and he will "check" me out every time we see each other in the hall, or lunch, etc. Last year I tried to "give" him my cell phone number by writing it on a piece of paper, folded it up, and put it on his desk (BTW it said my name on it). He opened it and gave it back to me!!! I want to write him an anonymous note telling him my feelings for him and put it in his locker when no-one is looking because I'm very scared of rejection and humiliation. Is there any way I can ask him without all of that??? Is there anyway I can find out if he likes me for sure???