There's two camps. One of which is a Brothel. I think it's to the left of your starting point where you meet Roche. It's only a couple of tents and the soldiers there ignore you. Pay the Madame enough and she'll let you access a tunnel which you take to get into the camp.
Spoiler:
If you mean later in that mission, Roche will distract the guards for you while you hide behind the nearby crates. Wait for them to go and follow the path behind the tents towards the kings. Once there, use the Aard Sign to break the barrels and run back the way you came before they see you, then just head into the tent.
This is following Iorveth's path by the way.
[Edited by Skyheart, 5/19/2011 1:52:16 PM]
--------------------------------------------------------------------------- "Remember the good old days when you could just slap Omni-Gel on everything?" - Shepard, ME2
"Not right now. Trying to determine how Scale Itch got aboard. Sexually transmitted disease carried only by Varren..... Implications unpleasant." - Mordin, ME2
--------------------------------------------------------------------------- "Remember the good old days when you could just slap Omni-Gel on everything?" - Shepard, ME2
"Not right now. Trying to determine how Scale Itch got aboard. Sexually transmitted disease carried only by Varren..... Implications unpleasant." - Mordin, ME2