Wire Color Coding System
Six wires come with track wiring. The blue and white wires are optional, and both wires can be soldered to an on/off switch or simply cut off the circuit board. The remaining wires are red, black, brown and gray.
Wire Hookup
The black wire from the reversing unit should be soldered to one of the motor's terminals while the red wire should be soldered to the other remaining motor terminal. The gray wire is combined with the wire from the center rail pick up while your brown wire is a combination wire.
Transformer
All wires lead to the transformer, which gives power to the train. Instead of plugging your train directly into the wall, you need a transformer to diffuse the current down since it is too powerful. Transformers also help to "transform" household currents to DC currents, which is what a lot of trains run on. Because your transformer connects directly to the household current, there are safety issues with the possibility of electric shock. You also do not want to do anything that could spark a fire.