If you're serious about making money online, start a blog. Blogging is one of the easiest and most sustainable income sources. As long as the blog is setup the right way, in the right niche, with the right content targeted at the right audience, and the offer is complementary to the content, you could make a tremendous amount of passive income from a blog.
To get started with Amazon affiliate marketing you will need to sign up with Amazon Affiliates. Then subtly market products on your site that are relevant to your niche and will be of interest to your audience. Make sure you only endorse high-quality products. If your visitors make a purchase on your recommendation but are not impressed with the item, you could quickly lose followers.