Unity game Mysql on a website?

Hi gang, got this complete and working on “LOCAL HOST” on the computer, cannot find any documentation what to put if the mysql was to put onto a website everyone only shows you how to do localhost and no one clearly explains hosting on a website (have my own site)
what dod i put for host name if is on my site.

www.mysite.com/online/Register.php (example)

$Hostname = “”;

$DBName = “”;

$User = “”;

$PasswordP = “”;

send the information to a WWWForm and as a field (WWWForm.addfield) and with it the WWW is the url link to the php file. Then in your PHP file use something like $_GET[‘User’] to get it from the field. do your authenticating then send a confirm message back to the form. Then back in Unity you can check whether that connection said that message.