Got a denial letter for unemployment, what now? after 15 years as a retail manager

I was told my separation was for misconduct, which is not what happened. 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?

File the appeal before the deadline, even if you are unsure. You can gather documents afterwards. That is the one part I would not wait on.