To Create a Web Distribution With a Manufacturer’s IES File

At the command prompt, enter lightingunits and set the value to 1 (American units) or 2 (International SI units) for photometric lighting.
Click Window menu > Properties Inspector.
Click Modeling tab > Render panel > Light drop-down > New Spotlight.
In the drawing, select the light. The properties for the spotlight are displayed in the Properties Inspector.
Under the General panel, change the lighting Type from spotlight to web.
Under the Photometric Web panel, select the blank text box.
Click the browse button and then select an IES file.
The light has been changed to have a web distribution with the web settings from the IES file.