add a background image on your USB

Open your flash drive

Copy a picture to it and rename it as test.jpg

Right click and create a new Text file, open it

Paste this code:

[ExtShellFolderViews]    

{BE098140-A513-11D0-A3A4-00C04FD706EC}={BE098140-A513-11D0-A3A4-00C04FD706EC}    

[{BE098140-A513-11D0-A3A4-00C04FD706EC}]    

IconArea_Image=test.jpg

Save the file as desktop.ini

Refresh by pressing F5 key