You may use your default username and password for connecting to your account and managing your files through the FTP protocol.
However, depending on the circumstances, sometimes you may need to add additional FTP user to your hosting account. This video demonstrates how to do just that. Remember, your HostGator cPanel will allow you create an unlimited number of FTP user account for free regardless of the hosting package you have with us. For more information visit http://hostgator.com
You can watch this video also at the source.