From the orders you found, Ulfar has learned that Olwir plans to capture a Stone-troll that stalks Rushock Bog and deliver it as a gift to the Dourhands in the north. The cow he stole from Filibert was bait to trap the creature.
'Who would have thought the theft of a cow would uncover a plot such as this? We must foil Olwir's plans, and if he has captured a troll, we must slay it!
'Fortunately, I have learned where Olwir and his dwarves are camping. They can be found in the north of Rushock Bog. However, getting into the camp and slaying this Stone-troll, if they have one, will not be easy. We will need help.
'Gather a party of warriors -- if there are any to be found in this land -- then return here. Make sure to gather sturdy warriors, for the battle ahead will not be easy.'
Olwir's camp is in the northern reaches of Rushock Bog.
Ulfar has decided that Olwir's plan must be put to an end and has asked you to gather a party of warriors to accompany him to the camp. Once there, he plans to inflitrate the camp and slay any Stone-troll Olwir's dwarves may have captured.
Ulfar is back in Needlehole.
Having succeeded in your quest, you should return to Ulfar to tell him what happened.