From the main Freeport Gate (WFP), head straight north. You'll come to a bunch of catapults and Ghostly Orcs. That should be the location to trigger it, unless the quest is bugged.
You can also go to there from the Graveyard newbie zone, which you can get to from Stonestair Byeway off North Freeport. Once you take the Commonlands exit from the Graveyard you will literally be right there.