First, you choose the domino from the top six, by pressing either from the '1', '2', '3', or 'A', 'B', 'C' buttons., above the dominos. Then you choose a numbered place, where you want the selected domino place. Then press to the numbered button. If the domino doesn't match, then nothing will happen. If you choose wrong domino, just press again the domino's button to unselect it.