Returno the Hunter's Reach shop in Dalaran and speak to Emmarel Shadewarden.
I sense the threads of fate entwined about you. Your destiny is tied to that of the ancient night elf who started you on this journey.
I can send you back to the city in the sky. From there, you must begin the task of gathering allies against the ravenous darkness.
Fight well, <name>. May Talonclaw serve you well.