-Connect a USB to console / Connect a source through DLNA
-Launch Media Player (either directly or through Settings>My Xbox > My background > Custom image)
-Navigate to source of your choosing (USB/DLNA)
-Navigate to folder/file of your choosing
-Select the jpg/png image – see it full screen.
-Once you are viewing the image full screen, hit the menu button.
-Select “Set as background”
-You will be sent back to the full screen view of the image. Hit nexus, see the image on Home.
You can download the Photoshop Document for the background quickly here.
The template looks like this:
3 layers including the box overlay, your work area and the background
For those who are curious, this is rolling out today for gamers in the Preview Program; for those of you who are not, you'll have to wait until November to get your customization on.