Voici une traduction ... Pour le succes/trophée le triophe des ombres . Il suffit de faire 5 job de la même catégorie pour débloquer les quêtes spécial J'espere vous avoir aider .
Source:
In order to restore the Thieves' Guild to its former glory and assume the title of Guildmaster, you must perform small 'jobs' across the four major Holds of Skyrim. To get a job, talk to Delvin Mallory or Vex - you can have one active from each quest giver. Once you have completed 5 jobs in a particular Hold, Delvin Mallory will offer you a Special Job in order to increase the Thieves' Guild influence in that Hold. Once you have completed all four Special Jobs, you can talk to Brinjolf to officially assume the title of Guildmaster. Completing a Special Job also increases the Gold available to all of your fences by at least 500 permanently.
Note: You are assigned targets at random, and you are not told how many jobs you have performed in any particular hold. Luckily, you can accept and quit jobs at will - use this to your advantage if you are assigned jobs in Holds you have already completed, and if you wish to increase your efficiency by matching the two Jobs to the same Hold.
(Pour ceux qui comprenne pas go google traduction)
http://elderscrolls.wikia.com/wiki/Thieves_Guild_(Skyrim)