Need help in adding ailerons to GP Old TImer 40 kit, it only has rudder ,throtle ,elevator. Any help would be appreciated. Thanks

First thing, if you're going to add ailerons would be to eliminate most of the dihedral in the wing.

Is this an unbuilt kit, an ARF. or what? If the wing is already built and covered, it might be easier in the long run to buy a new wing kit and build the ailerons in as you go.

If adding them to an existing wing, or adding them to new construction then you'd want to add double ribs and spars "around" the new ailerons.

This graphic should help a little.
Good luck,
Dennis-