The name of the database, it's username and password are stored in the
/include/config.php file

The installation requires a MySQL database, if you don't have one, one needs to be created, otherwise you may use an existing database to house the 13 tables used by the script. You can even have multiple copies of this script using the same database, providing you set the table name prefix to a unique value for each installation. It is normally no problem having several scripts sharing the same database.

Once you have the database name, mysql user name and password, enter them into the include/config.php file, then use your browser to view the /docs directory, there you will be able to create the necessary MySQL tables and prepopulate the categories used.