[Therion] Creating a namespace for an existing wiki page so it's images can be stored local to the page and not in the root

Hi Can anyone give me some pointers how to add a namespace for a wiki page that does not already have one? This would save me from having to load all my images into the root namespace thereby cluttering it up. I have tried to follow the examples at http://www.dokuwiki.org/namespaces but when I try it out nothing happens. Thanks Bruce