Appeal deadline questions after an unemployment denial after 10 years as a retail manager

I got a denial letter last week saying I left my job voluntarily, but I was let go as a retail manager. I am in Kansas City, in case local advice matters. The letter lists a deadline and a hearing process, but it is hard to follow. If you have appealed before, what helped you prepare?

Stay calm and stick to facts. Mine lasted about thirty minutes and felt more like a conversation than a trial.