Ok, here is a quick walkthrough for the Peasant Uprising quest scenario:
After receiving the quest, go to the world map and send an army (with Hero) to the quest location.
Enter the quest location, there will be a brief cinematic.
Follow the road north from the spawn site, you'll be ambushed by a few peasants and archers, they will retreat when you kill some of them.
Follow the retreating peasants across the bridge, you'll encounter a larger group of massed peasants and archers. They will again begin to retreat once you've killed most of them.
Follow the peasants to a small camp to the north east.
Fight the peasants until they are dead or surrender.
There will be a brief cinematic with Sir Lentoth at the end of the scenario.
Return to the worldmap and go home.