Now that you have decided, at least tentatively, what information you plan to present in your essay, you are ready to write your thesis statement.
The thesis statement tells the reader what the essay will be about, and what point you, the author, will be making. You know what the essay will be about. That was your topic. Now you must look at your outline or diagram and decide what point you will be making. What do the main ideas and supporting ideas that you listed say about your topic?