Step 1: click on this link: http://www.shareasale.com
Step 2: sign up for the program. If you don't own a website, Twitter and Facebook accounts also work. If you want a detailed walkthrough of how to sign up WATCH THIS VIDEO: http://www.youtube.com/watch?v=ap1iGna1UFI
If you don't have a website, or use twitter or facebook, then use Buddhaboard.com and provide a proper email address in step 3 of the sign up process.
Step 3: Up next add Buddha Board to your vendors. If you'd like a detailed walk through on this, watch this other video: http://www.youtube.com/watch?v=3hu_LdaUXxM