How can I write a good thesis statement about a specific aspect of "The Necklace"?

A thesis
statement is meant to state your main argument and the points you will use to support that
argument.  There are many specific ideas you could write a thesis statement about for
"," and then you need to add your supporting points.  For example, one idea that the
story supports is that the necklace is a symbol of not being satisfied with what one has in
life. Another is that the story shows how dishonesty can ruin lives.  Still another idea is that
"The Necklace" can be nicely compared and contrasted with the story of
Cinderella. 

Once you settle on your particular idea, you will need to add
your supporting points.  The idea that dishonesty can ruin lives might turn into a thesis
statement like this:

In "The Necklace," Madame Loisel, her husband,
and her friend are all dishonest in some way, and this leads the Loisels to years of
backbreaking work and dishonor. 

Once you have your thesis statement, you can
use it as an outline for the body paragraphs.  In my example above, I would have first a body
paragraph about Madame Loisel's dishonesty, then a body paragraph about Monsieur Loisel's
dishonesty, and finally a body paragraph about the friend's dishonesty.  In your conclusion, you
will remind your reader what your thesis is and give the reader a brief review of your
supporting points.  This is a great story to write about, with much meaning that you can share
with your readers.