I've done it! I'm so excited! I've done my first ever piece of animation!
The most simplest thing, was getting the ball. You can't just animate any polygon shape you create. It has to have certain properties that are defined in a rig - which is basically the framework to tell the animator what bits can be moved and how. So, the ball I animated can squash and stretch from the top of the bottom, without losing it's mass. Very clever.
We used a site called CreativeCrash.com which is free join, and allows you use rigs added to the site from it's members. Brilliant, isn't it?