The following will guide you through the process of changing nameservers through some popular registrars:

GoDaddy.com

• Once logged into your account, go to Domain Manager.
• Click on the domain you want to transfer to our nameservers.
• Click on the "Nameservers" icon on the top menu.
• Choose "I have specific nameservers for my domains" and enter the two nameservers you were given in your welcome email. Leave the third and fourth boxes blank.
  
• Click OK

Register.com

• Log in to domain manager
• Your domains will show on the left hand side of your screen. Click the domain you want to change to our nameservers.
• Go to the top menu and click "Modify DNS".
• Select check boxes to delete current nameservers.
• Enter the two nameservers you were given in your welcome email in the first two boxes below,
• Make sure you have access to the email they will send confirmation to then hit submit.
• One the next page click confirm DNS change.
• They will send an email to your account on file. Go to that email and follow the link provided within 3 days to confirm the changes or your request is automatically voided.
• The email link will take you to a page where you click confirm one more time and you're done.

Enom.com

• Once you're logged in to your account, under Account Hightlights, click on the Registered Domains link
• Click on DNS Server Settings. After Use our Name Servers? click on the radio button next to Custom.
• Enter the nameservers you received in your welcome email in Name Server 1 and Name Server 2. Leave Name Server 3 4 and 5 blank. Click the save button.
• A pop-up window will prompt you to confirm the change. Click on the OK button
• You will be returned to the previous page and see a message confirming your changes were updated successfully.
  

NetworkSolutions.com

• Once logged in to your account, click on the Domains button on the left side of the page. Click manage Domain Names.
• On the Domain Details screen, go to "Change domain point to:" and click on the Desgnated DNS radio button. Click the Apply Change button.
• Click the Move DNS button.
• In Name Server 1 and 2, enter the two nameservers you received in your welcome email. Click the Move DNS button.
• Click the Save changes button.
• You will receive a message that your changes have been submitted.