These are the controls for each lamp. They set light polarity, light intensity, highlight intensity and the light colour. The first ball on the left, underneath a lamp is the light polarity control. Click the ball to switch between the two. Positive polarity is the default setting and this makes light from the lamp shine light onto the sphere.
Negative polarity makes the lamp suck light out of the sphere.
The next ball along controls the amount of light from the lamp. The third ball controls the highlight intensity. Click and drag to make your highlight brighter or softer. The fourth ball controls the colour of the lamp. When you click on it a colour picker appears and you can set the colour of the light the lamp projects.