Now that was figured out, I could start building.

Note that the Banshee wing is built upside down on the plans. First thing is to pin the top spar in place. I consider this spar to be the foundation of the wing. After all, if it's not straight, you won't be able to build a straight wing. To ensure that the spar is straight, I first pin a long metal ruler down on the plans and then pin the spar against it.