I helped a friend rebuild several walls / replace windows in his now Ex wife's house a few years ago after they got hit with termites. You obviously will need to have all the siding off of the house to do the job. Due to being in wind zone 1 for hurricane protection he had to get storm rated windows too... They go on pretty easy. Just make sure you tack it in place, make sure it stayed level, and operates fine, throw a few more nails at it, test again, then finish it up...
Trying to follow the example of the master...