Top (left to right: C.C., Kallen Stadtfeld (alias: Karen Kōzuki)
Bottom (left to right): Shirley Fenette, Kaguya Sumeragi

In making this wallpaper in paint program, I used the line tool to make a cross at the centerpoint, which would break the background into 4 spaces. Then I cropped out an image from an scan I found at animepaper and placed it at the center, then drew around the edges of the anime image with line tool. I used the fill-with-color tool to color the spaces of the background, using colors green (hair color of C.C.), light brown (hair color of Shirley), dark blue (hair color of Kaguya), and dark red (hair color of Kallen, if not mistaken).

Enjoy the wallpaper!