Denied unemployment, how do I appeal? after 13 years as an office manager

I got a denial letter last week saying I left my job voluntarily, but I was let go as an office manager. It has been weighing on me all week. The letter lists a deadline and a hearing process, but it is hard to follow.

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.