Private nameservers (for example ns1.yourdomain.com) brand your hosting and hide the upstream provider. There are two steps.
1. Register child nameservers at your registrar. In your domain registrar's control panel, find Register Glue Records or Child Nameservers. Create ns1.yourdomain.com and ns2.yourdomain.com, pointing each to the IP addresses listed in your welcome email.
2. Create A records in WHM. Go to DNS Functions > Edit DNS Zone for your domain and add A records for ns1 and ns2 pointing to the same IPs. Then set these nameservers as your defaults under Server Configuration > Basic WebHost Manager Setup.
Glue records can take a few hours to propagate. If the exact IPs are unclear, open a ticket.
