If I have a blog that is getting 100,000 page views a month that means that I’m probably getting at least 50,000 people to the site (most blogs will do between 1.2 to 1.4 pages per session). That means I have to try and get some small percentage of those people to buy something from me if I really want to do well. If I can’t get them to buy something then (in some cases) I have ads running on the site that will make me money anyways.
Once you sign up to become an affiliate with ClickBank, you will immediately be able to browse the different products available to sell. ClickBank has tens of thousands of products available, so in the beginning it's helpful to search by niche and commission percentage until you locate offers that you want to promote. Make sure you take the time to look at the vendor's sales page before promoting their product. They might be offering a 75% commission rate, but if their website doesn't look trustworthy or put together you aren't going to generate many sales, no matter how much traffic you drive their way.
I have been making money online for over a year now. Not in the big time yet, still consider myself to be learning my craft. I was doing it really ineffectively (using adsense and amazon along with a t shirt affiliate deal) and driving traffic almost exclusively though facebook. Probably averaged about $800 a month over the last year, mostly because Christmas brought an absolute ton of t shirt sales)