Pick an event from the story that is significant for the character and write a diary entry that includes the character's thoughts and feelings about the event. Not having very much money makes me vulnerable. I do not want to end up like the homeless people I see here on the street. I am going to have to get serious about finding an apartment and a job. The overall message you received is the theme.
All books have themes.
There are many themes that emerge in literature, and most books have more than one theme. Pick one thing you learned from the book and write about that. Write a two paragraph response about one of the themes of your book. In the first paragraph state the theme and give examples from the book that support the theme. Bill did not give up his dream of living in New York even when he had to live on the streets for two weeks.