Thieves guild

Ok I've looked at I think all topics of thieves guild. I have the thieves guild quest but cannot find it anywhere, how do I find it where's best place or town to start in?
The forum for all Redshift games.
http://www.linux.redshift.hu/forums/
http://www.linux.redshift.hu/forums/viewtopic.php?f=2&t=1413