Choosing a specific niche and then associating yourself with an affiliate program like Amazon Associates or ClickBank is where and how to start affiliate marketing. You'll receive a special link, and when individuals buy a product through it, you'll be compensated with a part of their purchase. But before you start to make money, you must build trust first. Now, you need places to promote your links and they are social media, blogging, or even Youtube. Always be consistent.