A few moments research will give you a result similar to this...
Unless you have installed some other app, the KF only comes with QuickOffice which will allow you to view but not edit Word docs and Excel spreadsheets. I believe if you want to be able to edit those docs you will need to upgrade to QuickOfficePro or some other office suite app.
An alternative is to use Google Docs website which will allow you to view and edit those files.
This is a how to mend it site - not - please do my research for me, May 2015
