Denied unemployment, how do I appeal? after 14 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. I have read a lot of threads here and could not find my exact situation. The letter lists a deadline and a hearing process, but it is hard to follow. If you have appealed before, what helped you prepare?

Keep everything in writing and save the confirmation numbers. It saved me later.