What is the mysql host name and connection?

Your MySQL host name is localhost
 
Create a Database , Database user on your cpanel. Then add database user with the MySQL database with required priviledges
You can use below format on  your database connection script

Eg : If you create a Database as myclass and DB username as cladmin, ( we use webpanel as cpanel username In the following example. you need to replace your own cpanel username)

• My SQL server (Host) : localhost
• My SQL Database name : webpanel_myclass
• My SQL Username : webpanel_cladmin
• My SQL Password : *****YourPasswordHere****