HTML is the language used to put things on a Web page. You will use it now but don’t panic if you don’t understand everything as it will be explained later.
The things you are about to do are just to get you used to the basics before you really start learning. Anyone who has hand coded HTML and CSS in a text editor before can skip the whole introduction and go to the tutorial for beginners.
This introduction might take you an hour or more but don't rush it as the foundation is always the most important part.