Doors and Windows - Door Lite

Hi, I want to install a door lite in an exterior steel door that presently doesn't have one. Has anyone done this before? Any help would be greatly appreciated.

Just installed in my daughters door and there easy to do.you can get them at www.mcmaster.com tel#x-xxx-xxx-xxxx item #1361a4 $27.51ea. it will give you a 10x10 veiwing area.ther called vision lite frames.all you have to do is get the glass or plexi.glass will look better longer.just get on line and check them out.it will also give you other options to choose.you can order right over the phone.all you do is cut a rough openig and the two pcs.are screwed together from the inside.they come allready primed.just paint the color you want and they'll look great.