To Create an Area Light Source

Select the Place Light tool.
Click the Area Light icon.
You are prompted to Identify Element to Convert.
(Optional) From the Preset option menu, choose a light.
(Optional) In the Name field, enter a name for the light.
Select the element to be converted to an Area light source cell. This is typically the element that represents the light fixture.
The element highlights, and an arrow indicates the direction of the Area light source.
Change other settings as required.
Specify the direction of the Area light source with the pointer and accept.
The light will shine in the direction of the arrow.

The element is converted to an Area light source cell.