In Office 2013, in most of the applications, there is a general options page. On this page, there is a place to select an Office Theme and the Office background.
The Office Background give a list of about 15 options, and the "Background is actually a grey-scale image that appears on the right-hand side of all office applications.
Is there a way to make and select my own backgrounds by either official or unofficial means?
See image below for what I'd like to change to an image I've created.