How to crack Keepass2 passcode

[RoundDuckMan]

I don't know the command to do this, and "--help's" output isn't helping too much. The part that's really confusing is how can I put in rules for the brute-force, like which kind of characters and ones I know of, etc, since I partially know the password, but I forgot a few parts (3-6 characters of a single kind), so I wonder how I can find the remaining bits. I don't mind if it takes a day or so.