Their are several different parts of html and it can take awhile to explain, so I'll just give you a general idea about it
The basics of html can be seen in the first photo in the Photos section, it shows how you need to setup your website to even start working in html.
The seccond photo shows these combinations of symbols and letters at the beginning and end of almost every statement. they are what is called tags and they are used to help web browers read and present the code that coders write. their are many different ones but I'll only go over a few.
The Heading Tag looks like the picture to the right. Unlike all of the other tags, the heading has 6 different versions of its self. Changing the number of the heading will change the size (as showen in the photo).