Each level will present you with a new challenge. You'll see the empty glass and a source of water, but there will be obstacles in the way. You'll need to use your creativity to draw lines that will help the water flow into the glass.
Remember, your lines need to be supported, or they'll collapse, and the water will spill! There's also a limited amount of water, so make sure enough of it reaches the glass to fill it up.
At the top of the screen, you'll see a bar that shows how much "ink" you have left to draw with. The less ink you use, the more stars you'll earn at the end of the level!
You'll use your mouse or finger to draw lines on the screen.