Whenever my car is in any gear, the lights in the gauge cluster won't turn on, I have to push the shifter a little bit back for the light to come on, but when I let the shifter go the lights turns off again.
^ Your looking for a big black cable that goes to the front of the tranny.
The bottom of the cable is attached to a lever on the neutral safety switch by a nut.
You'll see that the lever has a slot in it, so that you can adjust the position of the cable.
Anyways what you do is loosen up the nut, move the cable up or down (it should be pretty close to the middle of the lever), tighten down the nut, and test the shifter (make sure it moves smoothly and goes into each gear).