Tell us your moment. Start right in the middle of it...this is something only you can tell us. Include your thoughts and feelings and sensory descriptions. SLOW It WAY DOWN. Tell me what color your shoelaces were as you nervously leaned over them that first day of school, the linoleum floor projecting your humidity frizzed hair back at you.
Then, make sense of the moment (or moments) as it relates to who you are- this is the "so what" aspect of your essay.
Pull out all of the creative writing skills you've gained! Your moment may show your character by the actions you take. As you write- if you get stuck, look to models and our "ingredients of the genre" (on the "studying the genre page")
Try out a few topics. You do not have to stick with the one you start with!
I have some organizers in the room, if you need them...but first, try just writing. You got this.