First of all, just in case you are asking What are nameservers? Now that is out of the way.
To make DNS changes at GoDaddy.com, log in to your account and follow this guide.
1. In My Products, click ‘Manage Domains’ and select the domain you wish to change.
2. Click the ‘Nameserver’ icon and select the ‘Custom Nameserver’ tab.
3. Enter the nameserver details in the 1st and 2nd fields, then click ‘OK’
Note: You need to enter a minimum of 2 nameservers.
Warning: Do not enter your IP address; this will cause problems.
Remember, it can take up to 72 hours for the changes to take effect.