The FireWatch page is separated into tabs of data that is presented in aTreemap Visualization. The treemap is a widget that proportionally sizes blocks in the display to represent the data for that tab. The largest blocks on the tab represent the largest data users. The data is sorted by the tab you select and the type you select from the drop-down list at the top right of the page.
Reference: Fireware Basics, Courseware: WatchGuard System Manager 10, pages 15, 34, 59, 181