The e-store builder comes with a built in affiliate tracking program that gives you the ability to have affiliates sign up directly on your site. These affiliates can then place one of your banner ads on their site which link to your e-store. Anyone that clicks on these banners on your affiliates sites and purchases from your e-store will enable your affiliates to receive a commission of the sale based on a percentage that you determine.
By accessing the sections from the main affiliate program page shown above you can totally setup your affiliate program.