Lights will take on the color of the surface that emits them, so if you use a blue light texture, it will emit light with a blue tone. The light above the flag... is, uh, a wedge?
Just out of curiosity, what kind of setting is this supposed to be? Seems a little odd to have 50-foot tall walls of plate metal. Perhaps you should make th ceiling a little lower, use a cement texture, and go for more of an indoor warehouse look? Try to aim for something a little more realistic. Also, the angled metal supports are overlapping the wood a lot and don't meet up cleanly. Looks like you probably used rotate. Don't ever use rotate for arbitrary angles. It's better to use clipping planes or vertex manipulation.
