It's hard to answer a general question like this. It would be much easier if you told us something about the essay you are writing. It may be easier to write the thesis statement after you've written the rest of the essay. Because a narrative essay is a story, it is supposed to be entertaining. The thesis statement needs to make the reader curious. It might be less direct than in an expository essay. It should prepare the reader, but not necessarily tell everything. Here is the opening of Jack London's essay, "Confession," from "The Road:" "There is a woman in the state of Nevada to whom I once lied continuously, consistently, and shamelessly, for the matter of a couple of hours." And that really is what the essay is about. It's about how London, then a hobo, told a woman stories to make her feel sorry for him so that she would give him food and wool socks and other things. George Orwell begins "Shooting an Elephant" this way: "In Moulmein, in lower Burma, I was hated by large numbers of people – the only time in my life that I have been important enough for this to happen to me. I was sub-divisional police officer of the town, and in an aimless, petty kind of way anti-European feeling was very bitter." Notice how he combines facts and feeling. In this case, because the title of the essay is "Shooting an Elephant" he doesn't need to put that into the first paragraph.

Step 1: Read the guidelines provided & some previous examples. :)

There's no magical way, but it's a good idea to find the idea you want to support. Then you have 2 or 3 arguments that will link your idea with the text, they will be your 2-3 paragraphs. Then by thinking how they go together, you build your thesis statement around this. "Through this and this, we can see that and it is supported by such and such" If you have time, it's best to write the arguments first, then go for your thesis statement, but it's not always possible... so you have to think where you want your discussion to go and build around that