To create a MySQL database:
- Go to MySQL Databases in your cPanel
- Under 'Create New Database', enter the database name you wish to use
- Select 'Create Database'
Your full database name and database user name will have your cPanel username and an underscore appended to the beginning of the database name / user name you enter.
If the user name for your cPanel account is "domainc" and you have created a database named "phpbb" and a database user named "bbuser" then the correct database and database user names will be as follows:
database = domainc_phpbb
database user = domainc_bbuser
For further information:
Please refer to the cPanel documentation for database features, here.