Four major items will be edited:
Items like Article, Basic Page, File, Staff, Visual Grid Item etc. are items of type "Content Type". These items can be created/edited by selecting Content > Add Content in the black admin menu bar and then selecting the content type.Think of these as individual pieces of content on your site. These as sometimes viewed directly (as in an article or basic page) and other times are used in a "view" (see below) that presents them grouped together in different ways.