Ok, I have never done this in the past but someone put it to me like this: (from the perspective of developing website architecture i.e. flow of PR etc.)

SITEMAPS ARE CRITICAL, if properly implemented = link on every page of site which links to a sitemap which links out to every important page on website. all pages on website are 1 page away from sitemap-
So how do I go about creating one?

Thanks in advance.