To create ftp account, go to fastdomain cpanel and Files > ftp account. Create a new login name and password, default root directory and assign quota to this ftp account.

FTP Accounts allow you to access your web site’s files through a protocol called FTP. You will need a third party FTP program to access your files. You can login to a FTP by entering fastdomainreview.org as your FTP host and the username and password of the account you wish to log into.

You even can create ftp account for your addon domain name too.

To upload files to server through ftp account, you have to use ftp client software like filezilla or cuteftp etc.

Go to Fastdomain.com