All you need to do really depending what size window you got in mind is, get a couple of Acrow props from a hire place and put a bit of timber through the wall a Brick or 2 above where you want to put a lintel 1 prop inside and 1 outside, tighten the props up to hold it and then cut the bricks out below it for the lintel , when its fixed and if its not too big Myself I would use a sizable bit of timber for a Lintel make good the wall again, Quite simple really! Done it loads of times!
Done this last year at the back of my garage to fit a door and window unit. I am no builder but just took my time and it ended up a decent job. The best thing was that I got the second hand door and frame (UPVC) fully glazed for nowt .
Vic
