No, not a tutorial, it's a real website where you can make an AdBlocker.
It is a ultra-simplistic app, and is written in about 60-70 lines. Check it out!
BTW, when you try read the guide in the preview below, it will fail. If you open the webpage in a new tab, it does not fail.
ABTW, when you try to download it, it will appear grayed out. It's not, you can click on it. But, it it does not work when you open it in a new tab, because of Chromium stuff. Instead, copy this link and paste it into your URL bar (no copy link address):