Denied unemployment, how do I appeal? after 7 years as a quality inspector

I got a denial letter last week saying I left my job voluntarily, but I was let go as a quality inspector. Any experience at all would help. The letter lists a deadline and a hearing process, but it is hard to follow. If you have appealed before, what helped you prepare?

I printed my emails in order and wrote a one-page timeline. The hearing officer kept going back to it.