I am 13 and bisexual. I'm sorta in the same dilema, except I've flirted before, just not with guys (so be careful with my advice: Flirting is an art and I've only flirted with girls) First, make sure he is gay/bi. Don't ask him directly, but start a conversation about a gay celeb or something. I'm under the impression you guys are friends? Invite him to a movie or party as a friend. Take him aside somehow and start a conversation. Get something out of his hair and compliment him on his shirt or eyes (just don't do it too much.) Touch his hand or arm occasionaly. Finaly ask him if he is gay.(in private, he may not be ready to come out yet.) Only do this if your sure hes gay or if he doesnt feel bad about gays. I know this is a lot, just don't be nervous. He's your friend/future-boyfriend so don't worry.
Ps: Stare into his eyes a lot! And smile. Good luck!
Ps: Stare into his eyes a lot! And smile. Good luck!