When you hit the GO button, a ball will drop from the circled red dot.  If you do nothing, the ball will just drop straight down and bounce straight back up.  You can control where that ball bounces by using the "direction" cubes.

You can grab them with your cursor and put them anywhere in the playing area.  Their arrows indicate where they will direct the ball.  Just experiment a lot and you'll see how it works.

Your goal is the get the ball to go into the big green hole using as few direction cubes as possible. "Par Score" means the "average" for most users. At first, you'll probably just want to get into the green hole any way you can.  Once you get good at it, you can try to make the "Pro Score" on each level.  

This game is set up differently than my other multi-level games...  On the opening screen, you can click the little squares to jump in at an level you wish.