I inserted a DNS Record on the Server (DNS (SOA)), so if this is what you are talking about, then I did it.
Thats only one part. The other part is to make your nameserver authoritive for that domains. You have to do this at the registry where you bought the domain name, by settings the nameserver records at the registry to point to your server. The exact procedure is different for every provider, so you might take a look into the help or manual pages of your domain provider for details.