Actually I had the same problem. I'll just add on here. When i go to Import pictures, i find the picture in my folder, double click it, and it immediately sends the picture into the database without giving me the option to make part of it (the background) invisible, Im pretty sure it will let you do that for other things, but for some reason it doesnt let me, or him it looks like, select it.
Also, i think it should be made clear (for me anyway) that the picture i'm trying to import is supose to be in the Battlers folder