im trying to get into the northen part of the second level of the catacombs a i heard i need to free him and then go back to the treehouse and help beraind(or whatever his name is)
The Baelnorn is on the lowest level. It is one of the later quests in the game.
It's automatic once you complete the proper quests and reach the proper area you will be teleported by him into his presence.
