How to measure your wall and enter those measurements here?
Starting from the left side of the wall, measure from the corner to the first obstacle that interferes with the wainscoting. Only include windows in the measurements if they will interfere with the wainscoting. If they land above the winscoting area, ignore them.
In the example below, we encounter a window that will fall within the wainscoting area. So we measure the first section width up to the window. Then we measure the width of the window (including trim) and the height from the floor to the bottom of the window. We then measure another straight section with until we encounter a door and make note of the door's width. Next we measure another straight section, followed by a small straight return section and indicate this as a 90 turn-out. Next we measure until we reach the angled stair stringer, followed by a measurement of the remaining width until this meets the vertical part of the stringer (and make note of that height).