You're not placing, you're destroying! At the top of the grid are three shapes. You need to draw one of these shapes on the grid to remove blocks. Click on a block in the grid and drag to make the shape. There are two different modes you can play:

• Classic: Each time you draw a shape and destroy a set of blocks, a new line of blocks will appear from the bottom of the grid and move everything up. Make sure the blocks don't reach the top of the grid!
• Static: The grid starts filled with blocks! After you clear a row, a new row of blocks will appear from the top of the grid. Keep making shapes and destroying blocks. Once you are unable to draw any of the three shapes at the top, it's game over.

You can clear out a row by clicking on the power-up on the right side of the screen. Once you use it, you'll have to clear out shapes on your own for a bit before you can use it again. As you clear shapes, the circle around the power-up will show you how close you are to using it again.