It's possible that you can't see the site because the DNS/nameserver change hasn't spread to the nameserver that your Internet Service Provider is using. As the set-up instructions in your Control Panel said, it generally takes 48 hrs for the change to spread web-wide.

Provided that you have waited at least an hour or so, it's also possible that there is something local going on on your end that's preventing you from seeing the site. Two suggestions:

1.) Clear the cache on your browser and/or restart your browser. You can find out how in your browser's help section. It may be storing old data for your domain name.

2.) Reboot/turn off and restart your cable/DSL modem and router (if you have one). Keep them off for a few minutes, and this will clear the stale DNS info out of them.