Below is a detailed set of instructions describing how to open the door on Jo's official site (updated 12/21/06.)

1) Click the eraser on the desk.
2) Click the doorknob in the mirror to reveal a Christmas Tree.
3) Click the top half of the main door to reveal a wreath.
4) Click on the top half of the mirror to reveal garland.
5) Click the spider webs to make them go away.
6) Click on the 4th chime in the window to reveal a key.
7) Drag the key to the knob to unlock the door.
8) The door will open to reveal a package.
9) Click the bow to open the package.
10) Click on the paper to play a game of hangman to guess the title of Book 7!