To configure your own name servers in cPanel/WHM please follow the steps below:
1. Make sure your VPS has a proper hostname (like "server.mydomain.com" where mydomain.com is a domain you own and added in cPanel/WHM). Do not use "mydomain.com". Please see this link.
2. Login to cPanel/WHM:
3. Go to Edit DNS Zone in the left menu and click on it.
4. Clic once on the domain you want to use for nameservers to select it and then click on the Edit button
5. Add ns1 and ns2 records as shown in the image below. Remember to change the 10.10.9.9 IP(s) with your VPS IP (you can see your VPS IP(s) in Hypanel). You can use 1 IP for both records if you only have one IP.
6. Save the DNS zone
7. You also need to add the nameservers ns1.mydomain.com and ns2.mydomain.com to your domain register. Go to the company you bough the domain from and setup ns1.mydomain.com and ns2.mydomain.com with the IP(s) you set at step 5 above.
8. Check to see if your domain has the proper namesrevers at www.intodns.com/mydomain.com (remember to change mydomain.com with your domain).