Create the morph

Make it the created shape key the active shape key (it must have a blue background) and enter edit mode. Here you can move vertices in whatever way you like for your morph. In the illustration i made the nose longer by selecting a view vertices at the tip of the nose, and drag them out with the proportional editing tool. Do not delete or add vertices in any way, or the morph will not work.

After you are done, go back to object mode. The newly created shape will disappear, you can check what it looks like by playing with the Value parameter of the shape key.