Where does Helmuth receive a position for work?
After graduating, Helmut gets a job at the Bieberhaus, which is the office of social welfare at the city hall. Helmut continues working in this office until his arrest.
Working at the Bieberhaus doesn't significantly factor into the story or Helmut's subversive actions, other than his discovery of a large number of reportedly-destroyed contraband in the basement, although it could be said that it serves as a useful and relatively low-profile cover for his activities. I'd like to be able to say that there was some sort of symbolism in this part of the story, but since it's based largely on a real person, there isn't really any deeper meaning that would have been intended on the author's part, and this is probably just a check to see if assigned reading has been completed.