Ok, so I've got what used to be an exterior wall (thanks to an addition it's now an interior wall) that is a solid brick wall. I need to put a door way in it, no door just a doorway. I'm wondering if I can DIY or if I need to hire somebody to cut the opening. Actually, I'm not worried about cutting the opening, I can handle that. However I'm concerned about putting in the header. What exactly is involved in this and how much skill do you really need to DIY?