I started by stamping the images from the Hero Arts set Be Happy with black StazOn on acetate. Then I colored it with window color in several layers until I was satisfied.
Then I stamped HA Magical bg in lime green on a white cardstock.
I then cut out the window from both the bg and a white card, making the one at the bg a bit bigger to make a white frame around the image. Finished it by tying yellow yarn beneath the image.
And here are some images of the finished card that shows the window colors in different lights (and the foam adhesive between the layers in one).