You need to do that with your domain registrar where you've registered the domain. To find out who is your registrar try our Whois service. More information can be found in our welcome message. Here is a copy of DNS section in our typical welcome message:
PRIMARY & SECONDARY DNS CHANGES THAT NEED TO BE DONE:
We have setup your domain in our server - all you need to do now is change your DNS Servers on your Domain Record with your registrar. When you reach a live person, say to them ... I have a domain registered through you and I would like to change my primary and secondary DNS listed on my domain record ... When they ask you for the new primary & secondary Domain Name Server settings, provide them with the following:
Primary Name Server: NSA.DAYANADNS.COM (204.50.14.2)
Secondary Name Server: NSB.DAYANADNS.COM (204.50.22.2)
Once this change is done, (it takes 24-72 hours for this change to take effect), your domain will be forwarding to your new hosting on the Dayana Networks Servers.
Note1: you will NOT be able to access your server until you change your primary and secondary DNS servers.
Note 2: If you registered or willing to register this domain with us (at www.dayanadomains.com) just ignore the name server changing, We will do it for you.
If you registered the domain with us (www.dayanadomains.com) no change would be necessary and everything will be set automatically.
Name servers may be changed from time to time, So please check with your welcome message before using above name servers.