So I was doing some research.

is there more of a standard?

Is it just what went well what didn't?

Is there a format? etc. etc.

No, there's no format. Write out what you want your team members to write:

1. What went wrong? What bad outcome resulted, and what can we do to improve next time?
2. What went right? What benefit resulted, and what does that tell us we can do even better next time?
3. Any other observations we can use to learn from and improve?

It's okay to name names, but let's try to avoid blaming and finger-pointing. Remember that we're a team that wants to improve, not only for ourselves but for our future teams since it's unlikely we'll all stay together forever.

Game Developer magazine used to have a “Postmortem” column. You can go back and read some of those.