I was quite confused as a traditional HTML programmer about the structure of NicePage page creation. It was so frustrating so I was almost giving up.
Then I went back to the Help tab and copied all relevant (no Joomla or Wordpress) pages to a Word document and printed it for calm and contemplative old-fashioned manual reading with a cup of copy in my favorite reading chair. And suddenly I started to realize some of the frustrating mistakes to create a new modern web-site for our small business. The apparent initial simplicity to just "create a webpage in minutes" was not a way to understand how the pages should be built.
So I suggest that you publish a full PDF manual out of your already existing on-line pages, that explains the logical steps, including why to use Blocks, Groups etc.