1. After download, extract the .zip to your preferred location. 
2. To insert a light into your Scene, Choose "File --> Append"
3. Navigate the the extracted .Blend File
4. Navigate to the object section of the .blend
5. Select the desired IES light
6. Press "Append from Library"
7. You will now find the IES light in your scene.
8. To adjust the softness of the IES, scale the mesh light and then apply scale with CTRL-A.

For further questions please contact me via email at [email protected]