Frankly finnish the tutorial area (Istan) and it should start saying "To unlock travel to Tyria take quest X from Y" when you enter Kamadan. This ofcourse requires you to have a copy of factions registered on the same account as your Nightfall is registered on.
i have prophecies, and i beat the tutorial, got to kamadan, and champions dawn. thats farthest i got. and the diggers place. i never got a message to tell me how to get to prophecies though.
You have to complete the primary quest "The Time Is Nigh" to unlock travel to other campaigns. This quest comes after the third Nightfall mission. Keep playing.
