These steps start with the tiles arranged the way they are when you first look at the box. If you've messed around with it, back away from the puzzle and zoom in on it again to reset it before you start.
On the left side, move the blank tile into the empty slot. Don't touch the left side tiles again.
On the right side, move these tiles in this order: 1, 2, 6, 5, 7, 1, 3, 4, blank, 6, 2.
Now click on the steel frame of the left side of the puzzle to close the two panels, and if everything's right, voila!