@ c4c:
There is a kind of manual included with Movie Gui Builder. Look for the about.PDF, it will contain most features, if not all of the program.
As for criterium/prerequisites, you need an internet connection, and if applicable set your firewall to allow traffic to and from Movie GUI Builder..
Also set your preferred sites in the 'Web sources' tab, and you should be fine.. Next step would be to customize the template if needed.. (for instance, I don't need info on aspect ratio, or MPAA ratings, so I moved those boxes out of the visible range of the image in the Screen Editor, and in doing so, freeing up some space for the other boxes and changing the layout and colors a bit more to my liking..