Help please? Invalid Format? |PS3 Themes|Forum|PS3 Themes

First of all I'd like to say that ps3-theme-builder is awesome and the idea of building your own theme is what really stood out to me. Anyway, I am really new to this and I've come across an error when I try to add a hd background to the theme builder. It says 'Invalid format'... and says its not standardised and that i need to re-save it. 

So I have a jpeg image that i want to use from a friend, which i downloaded from his Facebook account. I save it as a jpeg as i download it, and i go on to open it in Photoshop, re-save it as a 1920x1080 jpeg file. Then when i add it to the theme builder i still get the error? Help? Is there something I've done wrong along the way. I only intend to use this one image, as a theme and I will probably keep everything else default as I'm extremely nooby.

Thanks in advance!