How to add a proper light?

Hello, I don't know how to add a "proper" light (by proper light i mean one that would be in a desired area and reflecting off of it and also not going through objects for example metal) because I'm trying to create a mod that add's a rear fog light to every official vehicle.

 

I don't know if this is any help for you:
Spotlight_Positioning

You have to have full shadows enabled for light not to go trough objects and of course light needs to have cast shadows set.

 

Thank you very much, but I'm not good in programming so I'll probably not be able to make my mod.

 

Placing spotlights is quite easy once you get the hang of it.

Don't give up! You can do this!

 

Ok, I'll try.
BTW I'm trying to make a rear foglight mod. If you want to, you know, you could help me out a bit. XD