Please, how does ads work?

[Jake]

Don't click your own ads, that's the quickest way to be banned for life from an ad program, they track IP addresses which would be the same for both of your computers, as well as suspicious patterns.

There are many ad systems that pay for clicks on your site, earnings may average roughly 1 cent per unique visitor. Google Adsense is the most popular for small blog style sites, though the $100 min payoff level can take years for a small site to earn. Sorry I don't know the tumblr ad terms, some sites split revenue, typically the sort of ads you can use on free sites is restricted.