What will i say to him???plzz help?

Theres this boy hu i like.i was talken to him during the summer but it was in a group and i havent spoke to him since. iv seen him around a few times but i dnt think he has recodnised me.i added him on facebook this morning and so did my friend and he has accepted me but not her.how do i talk to him on facebook just to get friends with him without being weird????????help