I set up the amazon account in the 90's. At the time they paid 15%. It slowly dwindled to 5% and now it has come up a pinch from that.
So here is the link i was first set up with:
http://www.amazon.com/exec/obidos/ISBN/0452011876/rs12-20
0452011876: This is the ISBN for the book. Although you can put an ASIN number there too. Each item on all of amazon has a unique ASIN/ISBN number.
rs12-20: This says "paul wheaton gets a kickback if these people actually buy something by following the link".
This continues to work years and years later. I just put the links out whenever I think about it (and sometimes other people put the links out for me). People buy stuff and I get an income.
Amazon has set me up with a few other numbers that I can use instead of rs12-20. I think my cast iron article uses ci12-20. That way i can tell how much is coming in from that page.
I set something similar up with ebay a loooooong time ago. And what it does or how it works is really confusing. But I do that for the cast iron page. People click on it to go buy cast iron. I can look at reports, but I am baffled at what it means.
Most of my articles generate zero income. The cast iron article and the diatomaceous earth article are two that do generate some money via the amazon and ebay links.
One time amazon called me into their offices to give feedback on new features they were working on. There were about eight of us there that were like me: they used the amazon affiliate program. The guy I was sitting next to had a website that was 20 times smaller than mine, but he was getting about 40 times more income than me. I was baffled.
So i can tell you about getting the links and getting a trickle of income. But to figure out how to get real money, you'll have to talk to somebody who knows a lot more than me.