Actually, it would seem that something went wrong while setting up your account, and the nameservers did not get set up correctly for your domain.
There are a few different ways to resolve this. But since this is a new account which (I assume) doesn’t have a website yet, I would suggest to do the following:
Go into the control panel of the hosting account, go to Addon Domains and remove the domain there.
Go back to the client area, go to Edit Account, and then Deactivate the Account.
Create a new account from the client area using the same domain name.
