The fields Position determine the location of the source. This means that the net is illuminated exactly from the front. A point in positive z-range is not advisable, since all surfaces would then be shaded. With the Ambient Light fields, the parameters for the background light are set. Intensity sets the intensity of the background brightness.
Reflection is the reflection constant for the background reflection.
Intensity sets the intensity of the light source. Reflection is the reflection constant for diffuse reflection.