This quest is fairly short. You need to go to Orotheim which is south-west of Morthal.
The main trouble I ran into is knowing were to go once I reached a roundish room at the end of the dungeon. If you turn around just under the stairs is a side passage that leads to another part of the dungeon that has the chest with the Fragment of Wuuthrad in it. Be sure to pull the chain to the left of the chest to open the fast exit.