The CA hinge needs to be in both surfaces before any glue is added to it. It's my understanding that once glue has been put on the hinge, you can't glue it again, so any hinge that has had glue on it will have to be replaced. Put the hinges in all of the slots on one surface, then line up the slots on the other surface and slide it onto the hinges. Once everything is set where you want it, put 3 to 4 drops of thin CA on the top side of each hinge, then turn the surface over and put 3 to 4 drops of thin CA on that side of the hinge. There should be step by step instructions on how to do this in the manual that came with your plane.