Processing

First i want to get how to place the circles which will block the main circle from you the mouse. After I have achieved this I will then look into how the circles dropped can block the chasing circle. Then after I will look into colour. Here is my first attempt at trying to create my vision. As you can see its not exactly going as planned. The circles aren't staying in the spot when clicked, it just changes with the mouse, never staying where it was originally clicked which is what I am trying to achieve. As you can see I tried a second attempt. I thought that maybe it was the placing of 'background' which made it so. But I was wrong. So back to the drawing board.