Every month, you'll receive a payment of your sales commission. It's free to sign-up, and all you have to do is set up the links, and I'll do the rest.
While putting an image on your side bar is a great way to start, you'll probably get the most out of the program if you actively promote by showing what you've made with E&E Patterns. I'll let you know when there are sales, too, so you can let your readers know. So many of you are already sharing your beautifully made creations, so why not earn something at the same time, right?
There's more information on the Affiliate Program page, but if you still have any questions, feel free to ask away.