There are four buttons just below the Toolbar. This is for use when you want to start a new web page. The main page might contain a course description and other generic information about the course. This is for use when you wish to change the contents of an existing page. Single click the page name, then select this button.
Category is an organizational tool.
This is for use when you wish to add a person as an author to a page. This will mean that they will have rights to your page through their database. Choose Create Web Page. This area requires you to select the type of document. Your choices are Main Document, Response Document, or Response to Response Document.