How do I create a simple HTML website with Github Pages?

Good morning,

I really don't understand. I've tried both online and with the Github desktop client, and I can't get it to work. There are videos from three years ago that explain it, as well as the official explanation from Github itself and the explanation from ChatGPT, and nothing seems to work.

Let me try to explain what I tried: Apparently, I have to specify my username as the name of my repository and write it in this format: username.github.io . For example, my username is now Johannes623, which means my repository should be called johannes623.github.io . The repository should also be public and contain a README file. So far, so good.

Next, enable Github Pages in the settings. There, select "Deploy from a branch" and then "main and /root" as the branch. Now go back to the README file and paste the website code there. Then go back to the Github Pages page and check if the website is accessible under the domain.

That's how it was explained to me. The only problem is, none of this works here.

Can someone explain to me in a very simple and structured way how to create a website? And ideally, also explain how to add a custom domain to this website? (I purchased one from another provider).

Thank you very much in advance!!