To put it simply: Make money by selling someone else’s product for which you will get commission.

Many people have become rich by becoming affiliates. You can try ClickBank, JVZoo, Impact, Commission Junction (CJ). They are Free and have huge database of products you can promote.  You can also get started right away.

You do not need a website but it is better to have since overtime it will build your brand. This will also help you gain more traffic over time with search engines and other websites.

So basically you share your links with others or using your website (if you have any). if people buy the product using your link, you will get the commission.