How to configure VPS ?

Hello everyone.
I am new to VPS and CentOs web panel,I believe , i have done all i can to setup my server, however, there remains an issue with DNS. so i am going to list all the steps i took.( domain name is not real )

Ordered VPS linux .
Hostname : vps.mydomain.com
ns1:ns1.mydomain.com
ns2:ns2.mydomain.com
Loged into vsp control panel and everything runs ok ..

using SSH , i installed Centos web panel. running OK
loged in using root to configure Web panel .

I believe , here as root , i need to define few things that will be the default setting used by users ( myself ) when setting up domains and hosting web site.. those default seting should be DNS setting like NS1 and NS2.

CWP > DNS Functions > Edit nameserver Ips.
ns1 subdomain : ns1.mydomain.com  ns1 ip : ip address set on my vps
ns2 subdomain : ns2.mydomain.com  ns2 ip : ip address  set on my vps

also created new zon for vps.mydomain.com from Add new zone section of Dns function.
i am not sure if i have done all correctly .. if i go my Mailserver manager , i get this message.
Your Hostname is: vps.mydomain.com and it resolves to IP: (ERROR: You don't have a valid hostname setup)
and i can not seem to resolve that issue ..

searching google, it point to creating a dns record for subdomain.. here that i have the problem , what subdomain is being referred to ?
i would greatly appreciate if anyone can walk me through to setup this vps server with CWP , so i can start with hosting my site.

Thanks

ok is been solved..
after so much search on the google .. found a answer to same issue as mine .. i had to save nameserver information again from Dns function > edit nameserver Ips , to regenerate A record . and working fine.