What is Herbert's profession? What does he aspire to do?

The answer to this can be found towards the end of Chapter 22. Herbert appears not to really have any sort of a profession just at the moment. He is "looking about," presumably to find some sort of work that he can do that will not be too hard.

Even though he really does not have a profession at the moment, Herbert has big dreams. He aspires to be a big shot in the shipping business. He intends to insure ships that travel all over the world to trade. He believes that he will be able to make a great deal of money in that way.