With one sole light source, set up the light about 5ft. away from the subject. You're subject now has only light on one side on their face. That side is the only side receiving the light, while the other side is left in a shadow. This classical lighting technique is used to create more mood in a photograph, and allow the viewer to sense a deeper meaning or emotion. This is a classic portrait pose, which can highlight a person's "good side," or make them look "larger than life".