Dragonborn is the first story quest in Skyrim: Dragonborn.
Head to any major city such as Riften or Whiterun
How to Start
You will be approached by a Cultist of Miraak
Why are these cultists claiming you are a False Dragonborn? Who sent them to kill you?
I've been attacked by a group of cultists. I need to see if they have any evidence of what prompted this assault.
I've been attacked by a group of people claiming to work for someone named Miraak. I need to find out why they are trying to kill me, and so I should look for the boat in Windhelm they used to travel from Solstheim.
Go to any main town, for example Whiterum, Riften, or Solitude
Walk around until approached by a Cultist of Miraak
Talk to, then kill the Cultists of Miraak
Loot their bodies for orders. You will find Cultists' Orders
Read the Cultists' Orders. The clue leads you to Windhelm
Go to Windhelm and to the docks there and talk to Gjalund Salt-Sage
Go to the marker in the center of the temple and it will complete the quest