"Where were you born?"
Translation:Gdzie się urodziliście?
There are some rare cases where it's ok to put it at the end, but for now, just remember that się is unaccented und should not be put at the end, unless it's a 2-word sentence.
I want to ask politely of someone I don't know well, so is 'Gdzie pan się urodził' correct?
Yes, that is correct. Note that if you are talking to a woman, it's "pani" and "urodziła".