I'm relli shy, how do i start a converation with him?

okaii so theres this guy :P, he's in my eng. cl, and he sits with me and my friend sometimes, but he mostly tlks to my friend. i don't relli know wht to say most of the times, when theres a conversation going on. im so shy i can never even think of a way to start a conversation with him. even when he's sittin' by himself for a sec, and can't even just walk up to him, and start a conversation, i have no idea wht to say! ever! sometimes i don't even know wht to say when i'm tlking to me best friends, and we're having a conversation, i get stuck and can't think of nething. and i would relli like to tlk to him, and mayb if i get to tlk to him a bit more, i would eventually get his msn and stuff... but tht requires me tlking/starting a convo.