Make sure you only do one wing half at a time. The spar needs to be clamped flat against each panel, and due to the dihedral, you can only do this one side at a time, and only on the bottom of the wing panel. While you wait for this to dry, make some servo mounts. These can be of any design you want, and some may opt to just SPAD them in (use cable ties or the like). I cannot vouch for this strength-wise, as I have only used wood ones.

Do the other side of the wing just like the first side. You should now have a full wing, with only the bottoms of the wing panels glued to the spar. Take your servo mount, and center it between the end of the wing, and the center. Mark where the servo will go, and carefully cut your hole in the bottom of the wing panel with a utility knife.

More to come later, I gotta get to work.

Servo Mount detail: