Welcome to the forum!
You have a locomotive with a dual wound field windings; one winding is an orange color wire, and the other is a green color wire. Make sure you can see both ends of both wires. One end of both wires will be twisted together, and the other ends of both wires will be free. You need to have this to get your locomotive to run and reverse properly.
If you do not see this, then your motor field winding may need to be rewound, or you can convert the locomotive to use a 3 position e-unit with just the wiring you have.
Here is the schematic page for the 200 series locomotives; the schematic for your loco is in the upper right corner.
http://pictures.olsenstoy.com/cd/ho%5Cd200a.pdf

Make sure you have the solder lug and nylon washer for the second field wire to electrically isolate the wiring from the motor frame.
See here for an exploded view of the locomotive and motor.
http://pictures.olsenstoy.com/cd/ho%5Cd200b.pdf

If you need further assistance, I can e-mail you a photo with the wiring drawn in to help in wiring up the e-unit and motor.

Larry