Needs borders (Ctrl-A, Image > Stroke 1px Black border)
Are these your first? They were better than mine =P. Still reearch some more into background use. Right now, unless I am mistaken, I see only images. Try go use filters first, then move on. The filters are a filler for which would be a normal brushing background.
Again, nice, and if you follow what I said above with what others say, you'll become great ^^.