Everything in my map is bright... Is this because of my skybox? Even the insides of buildings I have made are lighted... how do I go about fixing this up?
Use a light_environment entity for light from the sky.
RAD is the process that performs lighting calculations for your map. In Hammer's simple compiler, it's called RAD; in the expert compiler, it's the $light_exe line. If you don't run RAD, the map will be in fullbright.