Create > Lights >
Ambient Light
Adds an ambient light to your scene.
A Maya ambient light shines in two ways—some of the light shines evenly in all directions from the location of the light (similar to a point light), and some of the light shines evenly in all directions from all directions (as if emitted from the inner surface of an infinitely large sphere).
Use an ambient light to simulate a combination of direct light (for example, a lamp) and indirect light (lamp light reflected off the walls of a room).
Create > Lights >
Ambient Light > 
See Intensity.
See Color.
See Ambient Shade.
See Cast Shadows.
See Shadow Color.
See Shadow Rays.