Create a text file named desktop.ini in the folder where you need to change the background. You may find a hidden file in that folder too with the name desktop.ini If present open that file and add the following code at the end

Code:

[{BE098140-A513-11D0-A3A4-00C04FD706EC}]
iconarea_image=adress if the image without the quotes
iconarea_text=colour of the text

The code will appear the following

Code:

[{BE098140-A513-11D0-A3A4-00C04FD706EC}]
iconarea_image=C:Wallpaper\yourimagename.jpg
iconarea_text=0×00FFFFFF