How do you navigate between task panes in Microsoft Office?

There is a Option called "Window'

If you click that in lets say Ms Word and have multiple docs open, they will be listed.

If you have Ms Word, Ms Excel, Powerpoint or any other application open, hold the ALT key and while holding the 'ALT' key hit the 'TAB' key a window will appear and show you the applications that are open. Tab to the hightlight the application that you want to go to and let go of the ALT key for the application to appear over the previous application.