Glad you asked! Clickbank is an Affiliate website, basically selling products made by everyday people like you and me, and then being sold all across the net by everyone. The best part is, that you get commissions up to 75%, which is nuts. I have a buddy right now that's making like $1,500 a month extra just on that alone. He does other marketing, etc.
Any who just search clickbank in google, once you're there go ahead and sign up at the top of the page.
Once you're all signed up you should get a confirmation link in your email, I forget if there is an approval process but I don't think there is.
So once you're signed up you go back to the top, log in and then go back to the top and click where it says marketplace. This takes you to all of the clickbank products, categorizing them by specific niche's.
There you can search and browse through tons of products you want to promote. Promote meaning you want to market, and essentially earn a commission from.
To promote a product, just click the green button that says promote. When you do this another window will pop up and ask you for a tracking ID. You don't need to worry about that. Just press create.
Next you'll see another window with a bunch of HTML code, etc. You want to Copy the top link.
What you just copied was your referral link, so now when someone clicks that link, they'll be redirected to the sales page with the product you chose, then they buy, and you make money. Simple as that.
To keep track of your links I would suggest going to budurl.com. It's basically a link tracker/organize/counter. Sign up for that (it's free) then the code that you copied from clickbank, just go to the top on your dashboard in budurl, and find the tab that says my budurls, then click add new bururl.
This way you'll be able to keep track of everything, and can see how many clicks you're getting.
hope this helped man!