how to turn on a light using part collisions? [closed]

ok, so im trying to make a lamp that turns on when a part on the train it is attached to goes through a certain part, and then turns off when the same part on the train goes through a different part, but i only want the one part on the train to be able to be able to trigger the lamp scripts, and i have no idea how to write a script that will be able to detect what part is touching the 2 trigger parts, and then if it is the right part trigger its respective script. also not sure how to make a script in one part turn on a light in another part. any help would be much appreciated