We have quite a bit of work to do to explain all of the capabilities of the CMS. I've started a document on the WIKI that will give you a quick overview. http://www.broadleafcommerce.org/confluence/display/BLC15/Content+Management+System
After reading the overview, take a look at the import.sql file specifically looking at the entries into after the comment "--CMS data". This will show you how the dynamic pages and content are setup for the demo application. Look at store.jsp for sample usage to lookup structured content.
We'll have more coming on CMS documentation but hopefully this will get you started.