Hi, Robert. I believe that I would start by choosing a prehung insulated steel or wood door. Measure the door casing and plan on toenailing a 2x4 stud at a spot 1" wider than the casing width. For the remaining area, I would contact one or more of the national window manufacturing companies for a quote on the light section all as one unit. You will want the best insulating glass for this that you can get. If the old glass lights were probably single strength and not insulated, they probably made the area around the door very cold or very hot.
You notice that I am saying to get this designed out and ordered long before you start construction. Your light unit will probably have a long lead time for manufacture so you will want to have it in hand before you start demolition on this area. You should just have to give them the new rough opening dimension and they should calculate the casing size for the new light unit. They will probably want to measure themselves, just to be sure.