If you host asks you to set the DNS to a couple of entries that look like the following then it is likely this article will help:-

ns5.ventrino.com
ns6.ventrino.com

Who is your name registrar?

First identify your name registrar.  Popular ones include namecheap.com and  godaddy.com.  If you don’t recognise these names use a whois tool to find out.  www.domaintools.com and www.coolwhois.com are simple to use, they offer an input for the domain name, press the button and a few seconds later you can read about your domain and listed somewhere you will find your name registrar.

Got your name registrar – what’s next?

As name regsitrars will use their own method for setting the DNS you will have to check their FAQ for more specfic instructions. Most are simple and within a few clicks the job will be done.

Changed my DNS but still goes to old server, why’s that?

Patience! Officially it can take up to 72 hours for servers across the net to update entries. Typically 15 minutes but this will be in perfect conditions. Your PC will cache a routing table as well, so while the Internet may have updated your PC can still send you to the wrong place (sometimes a restart can clear this).