I recently purchased a used domain and would like to recreate the domain's
site, complete with original structure, permalinks, categories and tags.  It
was used for a Wordpress blog.  

I have downloaded the original site's contents with WebHttrack.  Wordpress can
import content from a variety of sources (including RSS feeds) but not from
simple html pages.  What is the best way to use the offline contents to create
something Wordpress can import?