After you have successfully obtained the log-in details for the control panel, please refer below link on creating your private nameserver.
1. Log into your Website Panel control panel using the resellers account.
2. Click on the Domain icon.
3. Select the domain used for nameserver and then click on the Edit DNS zone records.
4. Then click Add Record and create the A record for ns1 and ns2 pointing to the nameserver of your hosting account as below.
5. Save and Done.