The host should be left as
localhost 
In regards to the creation of the database, username and password, please read below:
1 - Login to cPanel
2 - Navigate to the MySQL Database section in cPanel
3 - Type in the name of the database in the textbox that correspends to "Db:"
4 - Click "Add Db" to create the database
5 - Look where it says "Users" (It should be right under the database creation section)
6 - Type in your desired username in the textbox that correspends to "UserName:"
7 - Type in your desired password in the textbox that corresponds to "Password:"
8 - Click "Add User" to create the username
Now that you have your database and username created, you will have to add the username to the database, please read below:
1 - Look in the top where it has a button saying "Add User to Db"
2 - In the left dropbox corresponding to "User:" you must select the username you created in the first few steps mentioned above
3 - In the right dropbox corresponding to "Db:" you must select the database you created in the first few steps which were also mentioned above
4 - Once you have selected the username and database, you will have to click the button saying "Add User to Db"
Now that you have everything done, it is time to install the script
Host - localhost
Database Name - "cPanelUsername"_DatabaseName
Username - "cPanelUsername"_Username
Password - Password
I hope that briefly explains how to create a database and username and add a specific username to a specific database
NOTE: This tutorial is for learning purposes only
If you plan to distribute this tutorial or add this tutorial to your website, please let me know before you do so
MySQL Database Tutorial - Adding a Username to a Database 
