First, you make the frame. Cut the cardboard into 2 squares, rectangles, or circles, each the same size. The frame should be a little larger than your picture.
Cut a window out of one of the pieces of cardboard. This is where you'll put your picture.
Glue the 2 pieces of cardboard together along 3 sides, but not on the fourth (this is where you'll slide your picture in).
Glue different types of junk onto the frame.
Slide in your picture and your frame is done. You can also paint it if you want.