As it says on the back cover:

"Follow Fido on his whacky adventures as he tries to build a machine to fly him to the Moon.  Look at the picture clues to help you guess what he's building.  Then simply pull and fold the tabs as shown here to see his machines pop out of the page in amazing 3-D."

(The photograph of the back cover, photograph No. 2, perhaps makes the back cover appear damaged. In fact, this is just a weird lighting effect which happened when photographing the book.)