Generally a person who wishes to make money from affiliate marketing has to signup as an affiliate with the affiliate marketing companies. Once you are successfully registered, verified and completed other simple formalities, you can start selling the products. Almost all top affiliate marketing companies give their affiliates different collateral and marketing material like your own unique affiliate link (through which products sold by you can be tracked), banners and text link ads for your blog or website, mailers and various other things. Your job is to just use this material and generate sales.
If you are looking for starting affiliate marketing than it is one of the best ways of making some decent money. If done with proper approach then it can also help you to make handsome income every month.