Imagine a certain brand of hammers (yes, the tool) becomes really popular for all the right reasons. Let's call the brand "Hammerhub". Now you want to know what is so special about Hammerhub and the hammers they make. To experience that, it doesn't help to read about materials, manufacturing processes or blueprints of Hammerhub or hammers in general. You have to use that hammer for sculpting – or at least rattling some nails into a wall.
If you have never sculpted before, you can start with any hammer of course. But it certainly won't hurt to learn sculpting with Hammerhub.
GitHub can be used to publish sites via GitHub Pages. Even better, these pages are processed by Jekyll, which allows to use Yaml data via Liquid-templating, writing in Markdown and even blogging. Add GitHub's online editing and creation features and you have a complete and very powerful web publishing toolkit in the the browser.
While doing your first steps as outlined on the coming pages, you will build a personal history in your first repository (more on what a repository or "repo" is very soon). And you do not even have to think about it. If you should decide to do more coding afterwards and want to learn how exactly Git works, you can check out your own repo and work with the already existing story of your very own commits.
Just follow along the steps, click by click and if something should be overexplained (meaning you already know this) – all the better.
If possible, find a peer
It's called "social coding" – and you cannot do that alone. In the material, there will be sections entitled "If you have a peer". Those are the parts that will show you what is so special about GitHub (and other online code collaboration tools, of course).
If you follow this guide on your own and not in a workshop, you can always ask questions by opening an issue on GitHub.