Two ways

On top the inner tube is stuck all the way through the outer tube and melted in the rear. you tie on the small tube right in front of the outer tube and use a soft connection tube to hold the hook.
Below that the inner tube is only stuck partly into the outer tube, which is cut at an angle. You tie right on the connection, and using a connection tube is optional since the hook can go inside the outer tube.
The cone goes on AFTER the fly is finished.