Pretty much, you need to meet these requirements:

BAN REQUESTS:
-SteamID/UniqueID of the accused
-Reason they should be banned
-Approximate time of occurrence
-Solid proof of said reason – videos and screenshots are great, and if you need to report the chat a screenshot of the chat works too. You can also give us a timeframe and request that we check logs, although I would much prefer the former. Use serverside logs only if you absolutely need to.

BAN APPEALS:
-Your SteamID/UniqueID
-Reason you were banned, if you know it
-Length of your ban, if you know it
-Reason you should be unbanned – This can be either a concession, an explanation, or a challenge to your ban reason
-Proof (if applicable). We may need proof in certain cases to confirm your explanation or challenge.