custom entities/help with bugs

[darkgirl134]

hi there!
im new in this kind of stuff, so i have some really basic questions. i recently got an idea to do my own custom story, but unfortunately i had some trouble with the lights.. how can i turn off a light when walking to some area or colliding with something and likewise (i mean turning some on) ? i tried everything i could think of..
also i'd like to put there some custom writings on the wall or pictures maybe, but i didn't find how to do it either. i know it may sound really stupid and it's probably really easy but i just began with it so please help..
thanx!