When adding a domain to cPanel, you will need to first configure the "authoritative nameservers" with your domain registrar.
Most registrars have a guide on how to do this, you can search their knowledgebase for the exact steps tailored to their user interface.
At the most basic level, you will need to:
- Edit your domain
- Remove the existing, default nameservers and/or change to "Custom Nameservers"
- Specify the nameservers:
After setting these options, the nameserver changes may take up to 24 hours to propagate. You may then add the domain to your cPanel account.
If your domain still doesn't work after updating your nameservers, please open a ticket.