Let me tell you something. It's a BIG world out there. Your school is a very, very, VERY small fraction of it. Think of this time in your life as practice for when you are older. Approach the situation as if the outcome doesn't matter, because in the long run, it doesn't. Be yourself. Relax. Have fun & just talk to him. You can do this. You talk to people all the time. He's no different. Good luck. (by the way, luck is where preparation meets opportunity, nothing more)
This is one of those questions that has no simple pat answer. It goes to the very complexity of your own psyche, and whatever strengths or problems lie within. Are you generally a confident person who has a decent idea about things you are adept at, as well as areas where your natural abilities are somewhat wanting? In other words do you know yourself and feel confident in your own skin? Now certainly we want people we fancy to fancy us. Sometimes this may be a daydream fantasy we wouldn't know what to do with were it to come true. Other times the object of our desire simply does not and probably never will ever think of us the same way we think of them. I've only touched on a few of the many facets of human interaction, so don't be discouraged; you need to be okay with yourself, and sometimes you may have to go' out on a limb and risk being humiliated. This is being human, and developing your own unique and confident character is your obligation in the crafting of a human being, yourself.