FTP Details
The FTP details you should use for your FTP client are:
Host: your main domain
User name: your cPanel user name
Password: your cPanel password
Port: 21 (It is the default for the ftp protocol so you might not need to specify it in your client)
Example: In this example, the main domain is example.x10hosting.com, the cPanel user name is user and the cPanel password is pass.
This is how you'd set the client up:
Host: example.x10hosting.com
User name: user
Password: pass
Port: 21