From Page 1:
* Home Screen uses “Linksheets” 1040x520 use *jpg or *png and remove the file extension and place into theme folder and re-zip
If you want an image to display from “Spotify” for example … download a Spotify image and resize it (as above)
save it as Spotify.jpg
remove the file extension eg. Spotify
unzip the theme, copy Spotify into the root of the theme folder, rezip the theme at root level without compression (aka.store) then reupload the theme and you will see a backdrop for Spotify service