I moved my websites from one server to another this week and I needed GoDaddy, as my registrar, to change all my website domains to the new nameserver. I did a Live Chat with GoDaddy and learned how to do that. You first need to create host names on the domain. To set host names:

1. From the MY ACCOUNT PAGE, you should see your products listed down left side of page, the first will be DOMAINS, to the right is a green MANAGE button, click that.
2. You will then be on page with list of your Domains, click directly on the first domain name and this will open DOMAIN DETAIL page.
3. Down left side towards bottom you will see Host Names, to right you will see MANAGE link, click that and then add your Host Names and IP addresses in the boxes provided.
4. You will need to give them about 24 hours, then you can start setting your domains to those Nameservers under Domains/Manage then Nameservers/Manage.