And I don't know what to do when I was trapped in the mansion north of the forest. The fake books. . . .
There are three fake books you can take off the shelves in the house in the woods. You need to place those books back on the shelves in a different order. Place the light yellow book closest to the mirror, the red book on the middle shelf, and the dark blue book farthest away from the mirror. After that the books will lock into place, and examining the mirror will give you the next piece of the puzzle.