To add a new content area to a page, they would need to edit the page code.
They would need to log in as super admin to the CMS Admin section.
select the content page and add a new content area, once the content area is created in CMS, click the developer notes link to get the code for adding that content area to a page.
copy that code and open the page in an editor, paste the code where the content area should display.
I Think you would be better of using a content template. see the following tutorial: