Hey I'm kinda new to C4d and I downloaded a 3d model that I have been messing around with and I want to put a light inside a "room" that is inside an other object without having the light affect objects outside of the room. Sorry if this is confusing. Please help.
if you turn on shadows for that light it will only light the inside of whatever object it is in. If you don't want shadows from that light you can Exclude other objects or only Include the 'room' by using the Project tab inside the light's attributes (which in earlier versions was the Scene tab)