To manage domains in WHMCS, follow the below steps:
-Log in to the WHMCS administration area.
-Go to the “Domains” or “Setup” section.
-Look for or create a domain.
-Manage domain details such as nameservers and contact information.
-Domains should be renewed or registered as needed.
-Set cost and TLD availability.
-If applicable, integrate with the domain registrar.
-Automate operations and monitor domain status.
-Use WHMCS logs or documentation to troubleshoot difficulties.
All details are explained at https://docs.whmcs.com/Domains_Management