You and your catapult are a good team, and you always manage to hit everything that can be shot. Now it's getting serious, because you're in a crammed stadium, filled with public who wants to see what you're capable of. So the thing is to show them what you can! Try to hit the star with your catapult, in as little attempts as possible and within time given. Then you'll pass on to the next level, that's slightly more complicated. You can even hit more stars at once: this earns you bonus points. Make sure that the elastic of your catapult is perfectly stretched, because you have to shoot the stone far enough to hit the star(s). Good luck and have fun!
Hold the left mouse button until your catapult is perfectly stretched, and release when you've determined the right shooting angle.