Create a mental ray area light using the standard procedure in Maya. See Create a Maya light source for more information. 
         
         To create a mental ray area light
         
         
            - Select Create > Lights > Area Light. 
            
- Open the  ( +a). +a).The  displays the selected light’s attributes. 
                
- Click the  tab, expand the  section, then expand the  subsection. 
            
- Check the option to turn the Maya Area Light into a mental ray for Maya Area Light. Select from the drop-down list the desired shape
               for the mental ray area light source. 
            
- Adjust the Area Light settings as desired, making sure to turn on the Visible flag if you want to make the area light visible
               in the final rendering. (Typically, light sources only illuminate a scene and are not visible to the camera. If you want a
               light to be visible (a table lamp or light bulb, for example) or to show up in reflections, you need to make it explicitly
               visible. This does not affect the light contribution of the light.) 
                See mental ray attributes for lights (point spot directional area). 
                
 Except where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
 Except where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License