Look into Easy Click Mate. It's what we use to manage affiliates and it ties into your Clickbank products. Basically once you set it up, you invite affiliates to join your affiliate program on yousite.com/affiliates for example (you can put this right into your product info in the clickbank marketplace). Here there will be a sign up form where they can register to be an affiliate and use any affiliate tools you set up on your site. This way you also get their email addresses so you can communicate with them.