There is a dome built into the renderer..it can be found under the Render Settings tab under Environment. You can get some HDRI at various places around the web for free....start at sIBL Archive and OpenFootage.net - the low res are still free. You'll find a bunch in a Google search.

My settings: Depending on the quality of the HDR image, you can turn the value in Environment Map from 2.00 to 1.00. That will cut down on the brightness right there. If you want to see the HDR image in the background, choose Finite Sphere w/Ground. Use the Dome Scale Multiplier setting to decrease the size of the background until it fits with the rest of your scene. Most of mine are good around 12.00 or 13.00. Also - and this is the big one - make sure the headlight is off on your camera. If you're using the Perspective camera you can't turn it off, so if you have the Perspective where you want it, create a new camera and copy the active view. Then go to the cameras tab, chose Headlamp and in the drop down choose Off rather than Auto.

Laurie

Edit: One more thing - you need to be sure that you change ALL the materials in your scene to Iray compatible ones, either by applying the Iray Uber Shader to existing ones or using the various general shaders included for a replacement such as metals, glass, etc.