If you just signed up for hosting then the most likely reason is that the DNS has not fully propagated yet. Recent changes in ICANN policies mandate that the domain propagation should be instantaneous but some registrars could be slow, You should wait at least 24 hours before worrying about it too much.
Make sure your domain's DNS servers are set to the one's mentioned in your welcome email.
If nothing works for more then 24 hours the please open a trouble ticket at http://manage.hostingfest.com