Good content is unique, engaging, and easy-to-use. You may have a bunch of old tech reports sitting around as PDF files. You could load those onto the hub. Are they good content? It depends.

As for creating places for your community members to learn about the Hub or the community's workflow, start with an article page. You can create article pages from the backend of the Hub. 

Let's start with some definitions. An Article is some written information that you want to display on your site.  It normally contains some text and can contain pictures and other types of content.

It is important to understand that the content of the site (article pages, modules, groups, etc.) is totally separate from the visual formatting (template) of the site.  It is best to think of text entered in the Administrator Interface as pure content and there is no need to style each individual component.