1999 silverado1999 door trigger wires

Haveing trouble on a ready remote 24927 using the door trigger wires, which are  (-). I talked to directed and they told me to use the dome light wire. There are 2 one orange and one white. I don't know which one to use or what polatity I'm looking for. This can't be that hard, I must be an idiot. Please help.

use a dmm.

I don't know what a DMM is. Please explain.

DMM is digital multimeter. A tool that is a MUST to have by your side when installing. White is switched ground (-) and orange is your positive. To be sure, set DMM to DC volts, put black test lead on the white wire and red test lead on the orange wire. Easiest spot to test is at a bulb holder that you can backprobe, with interior lights on, you should have a 12V reading. If the orange was (-) and white was positive, the DMM would show -12V.