There are infinite lighting possibilities with HDRI images. You can rotate the HDRI into many lighting combinations. Increase/Decrease intensity.
This is the complete lighting setup for VRAY using a domelight(HDRI). Three lights, a ground plane, and a camera. There is one Dome light where the HDRI is pulled into and two lights that are hovering over the scene(they emit light color).
An image attached once you download this file will show how to access the HDRI and how to position it. You must first click on the Dome light then go to the attributes of the light(CTRL+A). Then follow the JPG provided.