If you have received a notification e-mail and it's been over 48 hours, it means either that you did not point your domain name to the right DNS servers, or that your ISP's DNS server has not yet been updated. It generally takes 24 hours for domain names to become active. This is just how the Internet works; there is no way we can speed up the process. This DNS change has to update all over the world.
If you haven't pointed the DNS by putting in our nameservers, you should have been sent an email on how to take cared of that. If you didn't for some reason or lost it, please look up the article on how to update my nameservers. Also we should have a video tutorial available on doing this.