Basically you can put anything you want into these four pages for the main area. What is shown is somewhat limited by the limited space on the screen for each quadrant. At the moment, scrolling within a quadrant is not possible. That's why you should try to show contents that don't need more room than is available.
In the example on the left we only have news: four pages, each containing the Cover Stories macro from the Enterprise News Bundle, but configured to show news from different sources. Sidebar and footer haven't been configured yet in this example.
If you are using macros that are not part of the Linchpin Suite for the main area, chances are that it won't work perfectly. In this case, please feel free to drop us a quick note via our support channel so we can look into it.