>>1737836Uh to be honest I'm not sure, I always use Photoshop and the Paint I have on my Windows 8.1 doesn't seem to have a transparency option at all. I guess you could get GIMP which is free and add a colored background as a layer in there?
The jagged white lines usually appear with bad renders. I added a black background to check for the white outline but can't really see one. Maybe it's because of MS Paint?