You have completed the necessary lessons all young druids are taught before they can adopt an aquatic aspect.  Go now back to your trainer, Mathrengyl Bearwalker, in Darnassus.  Show him your pendant and prove to him you are ready to learn what he has to teach you.  He will complete your training, allowing you to become one with the water.$B$BGoodbye, young druid.  We shall speak again.