Oh, thatt is a cool idea. I was thinking that the Gatsby thing would be the thesis statement, made near the end of the first para, but I think Sean's idea of putting it at the end is even better.
Also, look online for what other people have written about this -- not to take their ideas as your own, but to build your appreciation of this poem. Then, look at some poetry analysis by googling "poetry analysis" and words from your list, such as "rhythm"... or:
"Poetry analysis" and imagery
etc...
By looking at other poetry analyses, you will get good at this, and soon it will be easy to do this sort of thing. Literature is something to enjoy, so don't be stressed!!
Kevin, EssayForum.com