Just try and sit down with him, one on one and chat and ask him if he would like to go out with you on __ insert day__ for a cup of coffee or whatever. If he says it's not a good time or takes a rain check, then tell him how much you would like to go out with him sometime. Shy guys (myself included) like quieter settings and one-on-one get-togethers. So dont just pop up next to him and ask him out and pop away. Be gentle and "smooth." lol. Or you can just ask him straight out without easing into asking him out.