the only way to get someone's personal address if FROM THEM! it is against the rules to give out someone else's information.
you could try to find it by seeing if the person has participated in any swaps and check with the hostess- or check with someone who seems to be (connected) with the person you are trying to find- but really the only (recommended/acceptable) way is to ask the person you want an address for - any other way is breaking the rules of personal content.