I need advice on guys!?

I am a 12 year old girl and there's a guy I met at school this past year who I like a lot. We are both pretty quiet and this is the first time I've ever been crushing- I don't have any idea what to do to express my feelings to him. I am not the kind of girl who would call him or try to get his number, I'm new to all of this. Please respond with good advice for what I am to do!!!!