I don't have the guts.?

There's this guy i want to ask to me school's freshman farewell. He's in 11th grade and we only talk in the morning at breakfast. I catch him starin at him alot, but i don't know how to ask him. Im a really shy girl too so im like really freaked the **** out about this. And earlier, my brother asked my who i was asking and i told him and he said that of course he'd say no. i still really wanna tho. any help and tips?!?! I REALLY NEED THIS!!!