This quest is fairly simple, but is confusing at times because of the way the game manages it, for instance The Midden is a confusing maze.
Finding the Midden
After speaking to Quaranir I had no idea where I had to go because you don’t get a quest marker. The quest goal is to “Find Augur Dunlain” but the map does not show where.
There are two people who I know of who can tell you were to go. The first, whom I went with, is Tofdir. I found him in the hall to the left of the courtyard of the College. He does wander around a lot so the way I found him is also by wandering around the place until I found him. You can also ask Mirabell Ervine but I am pretty sure she will just tell you to keep your nose out of this business.
Navigating the Midden
As I said above The Midden is not at all linear and it is east to get lost. I found my way through it fine, but I am not sure if that was just luck or if it is actually easy to do. I suggest you watch the video at the bottom of this page if you are having trouble with finding your way through, this particular section starts at around 3 minutes and 45 seconds.
Just before you get to the quest marker a locked door will be in your way that you can’t lock pick open. If you try to open it you get told that you perseverance will only lead to disappointment, but if you try a second time you will be let in.