Finding the Rogue Encampment actually involves completing a very short quest. First, the player needs to head to Vennerwood, and head south from the entrance out of Fenyndell until they reach a dock with a boat.
Just north of the dock is a small house with a crack on the roof. By falling into the crack, you will find a captured Rogue. The Rogue will ask you to go get his cell key and free him.
The cell key is located in Norsche Canyon, in a small cave at the western end of the canyon. Enter the cave, walk past the bandits and bandit leaders within, and grab the cell key. Then, head back to the rogue in Vennerwood and use the key on the cell door.
Talk to the Rogue after unlocking the cell and he will ask you to meet him again in a secret underground passage under Vennerwood, and give you a key. Head directly north from the cell until you see a small house enclosed by trees near the entrance back to Norsche Plains. In that house is a small cellar door - use the key on the door and follow the passage to find the freed prisoner, who will invite you to join the Rogues' Guild if you are a Rogue, or otherwise give you some starting gold.