What is about this thread topic that people make it in here (Arcadium, like is this the hustlers forum).
Anyways there are multiple ways you can make money online. One of the popular ways is being an affiliate. Clickbank.com is a service that hooks you up with companies looking for affiliates to promote and sell their products. Generally you get paid per sale of the product through the link they provide you. The easy thing is signing up for an account and picking products the hard part is actually promoting and selling. There are many tactics you can use to sell using youtube, facebook, and twitter. The most common way is to create your own website and/or blog related to the content your selling, write a ton of articless related to the content, fill the articles with appropriate "google" keywords to get the rankings of this site on the top pages of a google search for this product. ALso creating backlinks helps as well. warriorforum.com explains this alot further and also blackhatworld.com has some not so moral ways of accomplishing this as well.
One of the better ways is to create your own product and/or product to sell. Imagine having a product and then having tons of people doing what I said in the above for you, with the right product in the right niche you can eat.
The most popular niches to promote products or create products in are health, sex (online dating, not necessarily porn), and making money. Alot of money is made in these niches and there's alot of competition but they are tried an true niches and there's alot of scraps left to be had in these niche.