What does it mean to "characterize the lifestyle of the upper class" in The Great Gatsby?I am trying to write an essay on The Great Gatsby, and I...

With trying to decipher the exact meaning of any prompt, I
think that opening a dialogue with your instructor would be the best course of action. 
I am confident that there are insights there which could be meaningful to you in your
study.  Overall, it seems that the prompt is fairly direct in trying to get you to
examine how Fitzgerald depicts the upper class.  In particular, I would pay attention to
how Tom and Daisy are shown along with others of the "flapper" era such as Jordan
Baker.  Of particular mention would be the description of Gatsby's parties, the people
that are there, and the way in which Fitzgerald, through Nick and his own narrative
voice, is able to highlight how "the rich live."  The focus on materialism, as well as
how the books in the library do not appear to be what they are, and other elements that
bring out the inauthentic and false nature of the wealthy might be particular examples
that can be used to highlight how Fitzgerald characterizes the lifestyle of the
rich.