So - you've registered, and logged in, and ... now you sit, scratching your head because the screen shows that you have a default puppet, but you can't get into any of the rooms to use it!
Relax. Not a problem. You have to either add a 'real' puppet/character or configure the default character. From the main portal page (the one with the list of chat rooms), click the Add/Delete/Configure Puppets button on the top right side. That will open the Puppet Management screen.