The first thing to do has nothing to do with a ball. This confuses some people. Anyhow you want them to learn to paw your hand to get the treat youre holding inside. Without saying a word, let them work it out. Once they do that get them to figure out using both paws. Then you can put a word to it. I use "Touch". Once thats done put a target in your hand. It could be a margarine container lid. Then you can move their target onto the practice box. Anyhow, thats the very beginning.