So you don't have to watch videos, I'll write it out.
When you ask for a job, it will be in a specific one of the big cities(Solitude, Markarth, Whiterun, and Windhelm.) Once you have done four jobs in each city, you'll receive a special job. You must do all four special jobs to become a Thieves Guild Master.
*NOTE: You can do any type of job you want.