Access to cPanel, scroll down to the "DATABASES" section, then clicl on MySQL Database Wizard
Add the name you want to use for your database. The actual name will be your cPanel username, the underscore symbol and the name you pick in this step. once you've written the name you want to use for your database click on Next Step.
Pick a username and password for the user that will have access to the database. Your username will include your cpanel username followed by the symbol underscore (in the case of this tutorial the username is "domain").
To pick a secure password you can use the password generator.
Click on create user to proceed.
Now you have to decide what kind of privileges to give to your user. A standard script needs all privileges to work properly. Once done click on next step