Retroarch Theme For PS3

Waasssaaa guys!!

I recently got involved in retroarch. For the past couple week I been downloading roms and customizing art works for it. The only thing I can not figure out is how to change the background. I change to XMB but can not add a custom picture. When I search for background the folder show “no item”. I am on the PS3 console. I do see the file I imported using FTP and I am able to scan it. Also I change the background directory to the wallpaper folder which is in assest(same place where I put my png photos). Any tips on what I am missing?

Also i seen a few post about custom theme for retroarch. Is there a website or YouTube tutorial on how to do this? I can find anything but people showing their final product.