Import from PHPNuke

I have transferred the News from my PHPNuke website to WP 2.5.1 using a script I found on the forum, but I’m having a problem with users. At the moment, all posts in WP have “1” as the user and a blank space after “by” when viewed on the site.

In nuke_stories there is a field “informant” which I was using to store the name of the author of a post. It appears from looking at the database that I have to transfer these names to wp_users “display_name”.

What I need to know is: what are the minimum fields that need to be entered in wp_users. Also must there be a matching entry in wp_usermeta, and if so, what are the minimum fields there?

I have read the database description but did not get the answers I needed above.

Thanks,
Peter