Just ask him out like you would any other guy. You two are only a year apart so that's not big deal. Although I think that it's better that you tell him your feelings before you actually ask him out. I believe that to be more mature and a little easier to get out of if he does end up rejecting you.
So first get more flirty with him. If you are already flirty, then maybe just say at that level. But if you lack that, then step up your game by flirting more with him. Do so for a while before finding a right time and place for you to tell him how you feel. Be sure that you two are alone and relaxed so he won't be influenced by friends or time when he answers you. And when you finally tell him, don't tell him your background story and everything about why you like him. Just simply say "I like you" or "I have feelings for you" and wait for his answer. If he just "okay" then you can somewhat pressure him to answer if he likes you back by a follow up like "so what?" and "what do you think?" But only use that when there seems to be a dead end in the whole situation. Aside from that kind of situation, wait patiently for his answer. And if he says that he needs more time, it's not because he doesn't necessarily like you but it could be that it came as a surprise to him. It's perfectly normal if that happens.
If he does end up liking you back, then that's great! Arrange for a date or something like that after that. I believe that it's better to know for sure that you two share the same feelings before going out. If you do it this way where you tell him your feelings, you'd know if his feelings are the same or not. If you just ask him out, he could just say yes but not actually like you. I know some people who just go on dates just because they're bored or because it's fun and have no intention to actually like the person they went on a date with or start a relationship.