OK. Time to build a wing
Because this wing is fully symmetrical, you will have to build a wing jig. The jig can be made out of anything straight, and will allow for the ribs to touch front ,center ,and back. Two straight sticks or some aluminum angle works well. Just tape down and make sure the two sticks are perfectly parallel.
At this stage the jig is not that critical to have, but it helps. However you well definitely need it when you put the top sheet on.
At this point , top and bottom doesn't matter. Just note the position of the wing pin slot in the center rib. The slot will be the top of the wing. But if you forget, we can make a new hole for the pin when finished.
More talking pictures.