The welcome tab lists things you can do with WWW Server. Feel free to click on any of the possibilities - you can always request help for them.
If you have runned the NT Service, but it has crashed, it will not unregister itself. In that case, there is no problem in simply restarting it. If you want to use the GUI server instead, click the blue link to unregister the NT service forcedly. Note that this will not remove the NT service entirely, so depending on the settings it might be restarted at the next reboot.