I have been fasley accuse of shoplifting, how can I sue for defamtion of character and public humilation, and obatain a copy of the store security

You can sue for defamation. That's clear. However, I don't know about "public humiliation." That's sort of included in the damages for defamation. You can also sue if you were falsely detained (false imprisonment), and possibly battery (if you were touched).  As for getting a copy of the store security tape, you'll need to sue the store first.