I made a collage in GIMP, here it is!
This is my best friend and her cat Mimzy, and the pictures is taken by me
I used the lasso and path tool to remove the background from the original photos of the girl and the cat,
and then i added them to different background.
I also used the rotate tool, scale tool, share tool, flip tool, eraser tool, dodge/burn tool, and I changed the colors and contrast.