"Put" can be either present or past, of course, but "posez" is the present tense for vous of poser. To say "you put" in the past tense it would be either "vous posiez" or "vous avez pose (with an accent on that e)."
And I hope you weren't offended by my response to you. So hard when we are communicating by typing at each other.
yeah, Antitone is correct. the imperative is a command, where as here, it's simply the present tense, describing what is currently occurring. French does not have a 'present continuous', in fact, not many (if any) European languages do. so, saying 'vous posez le chapeau' is BOTH 'you put down the hat' (which, because the past tense of put is put, can be interpreted in English is present or past, but cannot be confused in french) AND 'you're putting down the hat'.