Write an article based on this "Add affiliation ads to your blog if you feel that your blog visitors would be interested in purchasing products from another website."
For example, if your blog is about books you could join Amazon's Associates Program, which is an affiliate program that will pay you every time someone goes to Amazon using an advertisement on your blog and makes a purchase. Usually you are paid a percentage of the purchase amount, similar to how a salesman earns commission for selling products that are offered for sale by other companies.