Drag your finger to draw a path for the ink. Pop all of the colored balls to beat a level, but avoid the black ones. You can bounce off the side walls.
Drag your mouse to draw a path for the ink. When you stop drawing, the ink will magically re-draw the shape you just drew, starting from where you stopped. It will keep moving along that path until it hits the top or bottom wall, or a black wall. Pop all of the colored balls to beat a level, but don't touch any black ones. Stuck? Try bouncing a line off of the side walls to reflect the shape you drew.