Affiliate Marketing Secrets

I sort of understand what it is. But could someone just chat with me on Yahoo! and teach me how to design my own to customize my web page for different websites i’m affiliated with? This is something i’ve wanted to learn for a while and google is not helping at all. I need to learn all about making a CSS code (if it’s called a code!?!?) from scratch. For example, if I tell yu what i’d like my page to look like, roughly, could you teach me how to make my own code for that?