Tail light wiring

Hi , recently bought a 1979 Kz650D, cleaned out the carbs, cleaned the gas tank because it was plagued with rust and runs like a beauty now. Since I got it running, I would like to start with putting some cosmetics to make it look sexy( even though its quite sexy already).I'm quite new to motorcycles and im learning as I go. I would like to put a new tail lights on since the style of the stock ones dont really fit the cafe look im looking for. The wiring confuses me >_< I'm not sure which wires are for the brake light or which wires are for the resistors. I dont want to jump the gun and start cutting wires until I know what is what. I don't have an owners manual since that got lost through the sands of time. If anyone can tell me of any characteristics of what each wire(like color) or if anyone has an owner's manual themselves, so I can figure it out myself, which is much prefered,since I'm still in the learning process and its much better if you take a hand on approach as appose to someone just telling you. Thank you for reading looking forward to a response

Well you really need a Manual to own and work on these bikes yourself. But the wiring at the rear for the tail and brake is simple. First the Black/ yellow wire is ground, then the Blue wire is the brake light, and the Red wire the tail light.
If you look in File Base at the upper right corner of the toolbar on this page, you may find a wiring diagram or one that's close enough.

Copy this for your toolbox:

Color Codes On Most Kawasaki’s (written for 1980’s bikes)

HEADLIGHT
RED with BLACK stripe, High Beam.
RED with YELLOW stripe, Low Beam.
BLACK with YELLOW stripe, the ground circuit.

BRAKE/TAIL LIGHT Can be an # 1157 dual filament bulb
RED, Running or Tail Light.
BLUE,(sometimes with a Red stripe) Brake Light Circuit.
BLACK with YELLOW stripe, the ground circuit.

LEFT FRONT TURN SIGNAL Can be an #1157 dual filament bulb
GREEN, Left front turn signal circuit.
BLUE, Left front running light circuit.
BLACK with YELLOW stripe, the ground circuit.

RIGHT FRONT TURN SIGNAL Can be an # 1157 dual filament bulb
GREY, Right front turn signal circuit.
BLUE, Right front running light circuit.
BLACK with YELLOW stripe, the ground circuit.

LEFT REAR TURN SIGNAL Can be an #1156 single filament bulb
GREEN, Left rear turn signal circuit.
BLACK with YELLOW stripe, the ground circuit.

RIGHT REAR TURN SIGNAL Can be an #1156 single filament bulb
GREY, Right rear turn signal circuit.
BLACK with YELLOW stripe, the ground circuit.