You might want to start off buying a 12v test light. They are cheap around $10-$20. Looks like a screwdriver with a light bulb in the handle. It will have a ground wire coming off it with an alligator clip. Clip that to a ground. Good grounds are 10mm machine screws under the lower metal dash at either side. You may see some white with black stripe (ground wires) going to these locations. Anyway, clip your 12v tester to that then touch the probe end to the red wire end terminal that is coming out from the shifter to see if it's hot.
Ok, let me back up. First here is what a 12 volt tester looks like. (I apologize if this is too obvious) :
Before testing wires ...let’s test the test light. connect the alligator clip to the negative on the 12v battery under the hood and touch the probe to the positive. Make sure the light comes on.