How do I insert a background image in to the grid?

To create a background image, you will need to follow the following tutorial:
https://milliondollarscript.com/article/alpha-blending-tutorial/

Then go the Admin, and click on the ‘Background Blending under the ‘Cool Stuff’ menu.

Upload your background image. (Click ‘Browse’ and then ‘Upload’)

Please remember to Process Pixels after uploading the background.