Take the various lengths of wood and set them side by side, leaving a narrow space between each one (3 x10.2 inches, 1 x 8.7 inches, 1 x7.8 inches, 2 x6.7 inches, 1 x7.8 inches).
0.2 inches and 5.1 inches from the bottom of the sign, using the little nails, fix the two 9.4 inch strips.
Using a drill, make 2 holes in the strip that's holding the bottom of the sign together (3 inches from each end) to make it easier to knock in the big nails.
Bore a small hole on each side of the sign (as seen assembled here), towards the top of the sign, through which you can thread the wire that will be used to hang the sign from the door.