In order to take advantage of his extra material, White must find a plan. In this case, a simple and effective plan for White would be to win some more pawns using his rook and bishop then probably give up the rook for the black bishop. After that, White would queen a pawn and then deliver checkmate.

This is not the only way of doing things, but it is simple.

Remember: you should always try to find the simplest way to win.