You can set the domain pointer at your registrar in the DNS settings actually, where you set the nameservers to ours. It will be called Domain Pointer or Domain Redirect -- or something similar. That is the recommended method for this.
However, the account you signed up for has the ability to use parked domains, I just verified that it is working. You should have the ability to add up to 10 parked domains on your account. Let me know if you run into any problems.
