All you have to do is register Domains, make your own Website, and join Google AdSense, in this situation Google places their ads on your site, and whenever some person clicks on these ads you get paid by Google.
You share in the revenue with Google. I mean you are only making pennies anytime some clicks on your ad, but imagine if you had a whole lot of sites.
I suggest you make a site which is meaningful, so you get visitors, because without visitors you make hardly any money at all. This site can have Google Ads, and obviously a smart site that draws a good crowd will make you money when they click on your ads.
Some good sites have their own sponsor ads or links on their sites, which generate income when a user goes to their site via yours. The payment plan depends on your deal with that company. It could be on CPC basis or even a percentage of their purchase price.
This is like any other business, you have to do some work, so that your site gets noticed. If you enjoy the internet then try it, I find it a lot of fun. Visit my site and see if we can help you at all. Opt-in to our e-mail and receive free information. We also have a blog you can contribute to, we would like to hear from anyone here with their ideas.
I guess you could start with a 3 or 4 sites, the cost is so minimal, it is almost worth it. See what happens. Foxtrot Domains even gives FREE Hosting when you buy a Domain from us.