It’s really a 3 step process. Let’s begin:-
1.) Copy Paste the following code in the notepad and rename that notepad file to desktop.ini (Just make sure when you paste this code, the Double Quotes are in Notepad format otherwise type the Double quotes manually from your keyboard.)
2.) Choose any image of your choice and rename it to back.jpg
3.) Copy Paste both these files (i.e. desktop.ini and back.jpg) into your USB device and make them hidden by selecting Properties -> Hidden Files.
That’s it. You are done.
Just REFRESH your screen and you will see your image on background.