1. Sign in to your GoDaddy Domain Control Center. 
2. Select your domain to access the Domain Settings page.
   
3. Select Manage DNS to access your zone file.
4. Select Add to add a new record.
   
5. Select A from the Type menu options.
6. Enter the details for your new subdomain A record:
   • Name: The host name or prefix for the subdomain. For example, enter blog to create a subdomain for blog.mycoolnewbusiness.com.
   • Value: The IP address for your subdomain. This will usually be the IP address of your hosting account.
   • TTL: How long the server should cache information. The default setting is 1 hour.
7. Select Add Record to save your new subdomain A record.

Most DNS updates take effect within an hour, but could take up to 48 hours to update globally.