The following window (MAC shown) will appear on your desktop:

The program only displays files with an ".ies" or "IES" extension. 3dOP Pro comes with ies type C files from ALLSCAPE preloaded with the program. The SL-23-20MH-BT5-SPT-.IES is selected. This is an in-ground fixture with a 20 watt BT5 lamp in a spot reflector. Note: It is a good idea to create your own photometric directory into the Documents directory.

Once the desired file has been selected, select "Open" or double click with your mouse on the highlighted filename. The file will be loaded into 3dOP Pro and displayed as shown below:

The green icon at the center of the grid indicates the 0,0,0 starting position of the fixture.