Presumably the following:
// HOST NAME OR SERVER ADDRESS
$hostname = "mysql.yourdomain.com";
// MySQL USERNAME
$dbusername = "username_you_chose_for_database";
// MySQL PASSWORD
$dbpassword = "password_you_chose_for_database";
// DATABASE NAME
$dbname = "name_you_chose_for_database";
Before installing anything using mysql, you will want to FIRST create the database. When you create the database you will choose a database name, a database hostname (it's a subdomain, really), a database user, and a password for that database user. Then wait for several hours, or as much as a day. I don't bother running any install script until I can click on the database in my control panel and then log into the database using phpMyAdmin. Once I've thus verified that the database exits, I can connect through the hostname, and the user/password work, THEN I run my install script.
Hope this helps.