The demo pages give you an opportunity to "test drive" STUMP. They are not functional in the sense that your actions do not affect anyone. However, they do give you a "look and feel" of how WebSTUMP interface looks to moderators.
When you click on "Begin test Drive!", you will be taken to the live installation of WebSTUMP, where you can see how it works for yourself. When you get there, read the front page and then click on "demo.newsgroup". demo.newsgroup is a special newsgroup where your actions would seem real, but with no effect on anything. So click away there.
You will be asked for a login and password. First, log in as user "test", password "test". Try out the interface for human moderators. Make sure that you see how picture moderation works.
After that, return to the main WebSTUMP page (hit the "return here for WebSTUMP"), and log in as user "admin", password "test". This will let you see how you can administer your newsgroup. Try adding new users, and edit some of the configuration files like the list of good posters.
This window will stay with you throughout the process.