Basic Concepts of Microsoft Word - from Shauna Kelly is a series of shorter pages, each covering one or two concepts. It is not all on one page, no.
If you are going to use Word on a regular basis, you need to learn these concepts, including styles.

Here is a link to the older website on those: Basic concepts of Microsoft Word: An introduction by Shauna Kelly, MVP
It is based on the older menu UI. I attempt to update it for the Ribbon UI but the basic concepts are the same.