You can use your provider's nameservers ns/ns1/ns2.myhosting.com and can add your domain from their control panel to manage the DNS. I could find a bunch of kb articles, demos & video tutorials in their site. Why don't you check that first.? They also have 24x7 support, which you can utilize also :).
However, since you have WHM access, I would suggest,
- Register your private nameservers ns1/ns2.forumify.com at your registrar with your VPS IPs.
- Ask your host to configure these nameservers in your server.
By this way, your server will be independent of myhosting NSs and DNS can be directly managed inside WHM/cPanel.
For kbs & tutorials,
http://myhosting.com/kb/Main_Page
http://myhosting.com/vps-guide/
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