The site you are looking for is not yet available.
Puppetfactory exposes port 80 on each user's container, mapped to a high port. This provides the ability to experiment with managing a service like a webserver. It does not actually run this webserver.
If you are seeing this message, it simply means that the container you requested is not currently running a webserver. If you are in a Puppet training class, this may be an exercise your class hasn't gotten to yet.