Begin by cutting the wires from the factory taillight. Cut close to the taillight to ensure you have as much wire as possible.

Of the x3 white wires, cut the two outer ones like so. 

Where you have cut the white wires, place some heat shrink or electrical tape around that area. 

Cut the rest of the wires to ensure they are the same length. 

Strip each of the wires from the plug.

Cut the solder off the taillight and strip the wires back.

Take the white wire from the taillight and twist the resistor to it.

Place a solder splice over it and insert the white and black wire from the plug. 

Heat the solder splice.

Take the other end of the resistor and twist it to the yellow wire from the taillight.

Place a solder splice over it and insert the green and yellow wire from the plug.

Heat the solder splice.

The yellow and green wire from the plug will meet with the yellow wire for one of the taillights and the green wire for the other taillight. 

This is how your taillights and resistors should be looking. 

Solder splice the rest of the wires in the shown orientation

Red - Green & White

Brown - Green

Black - Red & Blue

White - White & Black

Green or Yellow - Green & Yellow

Cover the wires in housing with the resistor hanging out. 

Complete process with the other taillight.

Your taillight has a small arrow in the corner. The brake light should be at the bottom and the arrow facing outwards.

Cover the taillight bolt in anti seize and place in the bumper like so.

Fasten to the bumper using the spring, flat washer and nut supplied.

Fasten the nuts. 

Take the resistor and rivet it inside the chassis channel using the supplied rivets.

Plug the taillights back in.

Your taillight's are now complete.