The note Jess gave you tells you everything you need to know, but you may need to do some research first. Read to the end of this hint for the answer.
The deal here is that the lock on the briefcase is a sort of digital readout like a digital clock.
Each clue in the paper Jess gave you tells you whether each bar of the readout is on or off. The final design won't be numbers, but it will get the briefcase open, which is the important thing.
You only have five minutes to get the case open once you enter the parlor, after which Clara will come back and you're in hot water. So if you want to go do the research yourself --
-- save the game as soon as you enter the parlor, only use a new name for your saved game. You can then restore an older saved game and run around the place doing research. When you're ready, restore the parlor game and go to it!
And here is the final design that will open the briefcase:
By the way, once you've opened the briefcase and removed the contents, you'll find that you can't leave the way you entered; for some reason, that secret passage only opens one way, Leave by the regular door and return to the cellar to talk to Jess.