I was typing while Ken was posting! Anyway his illustration is better than my explanation.

If it's an ARF the hinge slots are probably already cut. If it's a kit you'll need to do it. If the hinge slots are already cut measure and mark the center of each CA hinge you made and insert them in the hinge slots on the stab up to the centerline you drew. Use straight pins on the centerline to keep the hinge material from going in too deep. Put the control surface on by lining up it's slots with the hinges. Remove the pins and flex the control surface and drip 3-4 drops of thin CA on each hinge. Flip it over and do the same on the other side. If you have to cut the slots yourself use a #11 razor knife and cut them just deep enough so the CA hinge will seat at the centerline you drew on them.