With Office Online, the files can be stored on Microsoft’s OneDrive cloud server or in a connected Dropbox account. If you use Hotmail, Skype, or another Microsoft service, you should be able to use the same Microsoft user name and password for Office Online. Microsoft’s free Office Online apps (including Word) work right in the web browser - as long as you sign in with a Microsoft account.
However, if you are creating the documents in Microsoft Word on the PC, just staying in Word might be the smoothest approach.