well first you create one in cpanel and then a folder will be created automatically with the subname .. there you would upload the new content
zzz.xxx.x10hosting.com would create a folder called zzz in your public directory
Hello, first you need to sign up for an account at http://x10hosting.com/freehosting.php
From there you will need to fill in all the information after you have signed up for the account.