In order to block ads in your browser you must first consult within yourself the ethics of blocking ads. A good way to do this is by universalizing the action you wish to perform. Suppose everyone in the world decided to block advertisements. Then the sites which rely on advertisements to pay for hosting will not get the needed revenue to keep the website online. This is not a good reality, so therefore there is no ethical reason to block ads from websites.
Now that we are under the assumption that you have no ethics and still wish to proceed with the tutorial, the next thing you must do is...