To earn a commission from any Amazon books you promote on your website:

1. Sign up for an Amazon Associates account:
http://associates.amazon.com/gp/associates/join/104-5828546-7026338?node=3435371/104-5828546-7026338

2. They have a tool that will generate a link that you can put on your website. This will be under your Associates account, in a section called "Build Links". This is actually a pretty cool tool; they have all kinds of links with graphics, without graphics, etc. available.

3. Copy-and-paste those links into your website's HTML code, or into your HTML emails!

That's all there is to it!