Denied unemployment, how do I appeal? after 5 years as a graphic designer

I got a denial letter last week saying I left my job voluntarily, but I was let go as a graphic designer. This is my first time dealing with any of this. My employer's version of events does not match mine, and I have emails that show it. If you have appealed before, what helped you prepare?

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

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