How Do I Ask This Guy Out?

Okay, so there's this guy I fancy that's friends with my best friends' best friend (lol). He's in one of my uni classes, I'm pretty certain he is gay. Anyways, I think I caught him looking at me one day and think there's a solid chance he's into me.The thing is, I'm in the closet and I'm sure he would suspect I am straight. I've never been with a guy before (I'm bi). I'm completely clueless as to how to approach this. Do I try and befriend him first or should I avoid the friend zone and just ask him out even though it would be awkward? Should I ask for his number? Is the friend zone even a thing with guys?? I'm so confused!