Film is Based on the Medium of Light
Without light, we don't have movies. Light can be manipulated, covered, controlled, colored, and it's intensity changed, but there is no argument among film professionals that light helps tell your story. It conveys a mood, setting, and time of day. You can put lights into many different configurations, but you must know about the basic three-point lighting plan (sometimes, a four-point plan) in order to understand how light helps tell your story. Here is my Power Point on Lighting Set up.