Here's a free e-book you can download to learn how to start making money from clickbank.
Getting Started with Clickbank
The first quarter of this e-book will explain how clickbank operates, introduce you the different features (ie, Gravity, Earned Per Sale, Referred and popularity) of clickbank and how to use these features to do research on products in Clickbank to find out quality products and products that sell well which will help you decide which affiliate programs to join.
The rest of the e-book will teach you how to use clickbank to sell your own info-product if you have created one and want to sell it online. Resources and tools you need to provide to your affiliates to generate sales for you.