To point the nameservers here, please login to https://secure.lightningbase.com and then click:
Domains -> My Domains -> Manage Domain -> Nameservers (tab).
The current nameservers will be listed. You can click the "Use Default Nameservers" button and then hit save and it will automatically update the NS. This change will happen very quickly, but can take up to 72 hours to propagate fully across the internet.