Each row, each column and each box needs all six shapes, one of each. Pick a shape from the row under the board: the squares that already have it turn blue, and the little number says how many are still to place. Look along the row, down the column and around the box before you tap. If a shape cannot go there, the square just shakes. Tap a shape you placed to take it back, or press Undo. Nothing counts against you.