Affiliate sales in PayDotCom work this way: 

A Vendor sets up his product by creating his sales page and including his product in PayDotCom. He determines whether or not he will allow affiliates, and the percentage of commissions he will pay those affiliates. 

If the Vendor allows affiliates, he will need to set up an affiliate page. This page is created within PayDotCom, and allows affiliates to sign into their affiliate area using their PayDotCom login information. 

Once the affiliate has logged into their affiliate area, they can get their affiliate link to use to promote that particular product. The link is actually a tracking link that redirects customers to the Vendors sales page. All affiliates promote the Vendors sales page, but the tracking link installs a cookie that tracks sales and credits the affiliate with the sale.