there should be a set of buttons and one will popup a litte menu on your display that has nothing to do with windows....
there will be two key options to look for, both rectangles, one with a double headed arrow laying horazontal and the other will be vertical in the second one.
you move the highlight with one of the buttons so one of those is brighter than the rest and push select, and then you can use a button to grow or shrink it, shrink it and do the same to the other...
then exist when you see your Windows XP fits inside your display