Up 2.5 in the endgame, how to break through?

Thanks everyone. Will go over this with him this weekend, and then set him against the engine as white and black.

first thing to do is to bring the rook as active as possible. Ra7+ seems logical. then, you can bring your bishop to f3 after protecting the c pawn with your king. by this setup, it's not too difficult for white to push the c pawn