How can I find out where an person bank at

There is no way you can find out where a person banks, that is confidential information.

how can i find out where an person bank at
Hire a private investigator.

Ask them. If you knowing someone they pay, you can ask what banks their checks are drawn from.

If someone asked me for information on a person, where they banked, etc. I certainly would not give them any information even if they gaveme a good reason why they wanted to know.