crushing on a boy

I have a crush on this boy in class. He is really nice and sweet to me but he can be a real ass and be a bit Imature. I know he likes me, it is super obvious. I wanna ask him out but he would be my first bf and I am only 13. should I wait for him to ask or just go for it? I am not shy but I am nervous about him saying no and telling his friends and me getting really embarrassed.