One thing for other folks, even though you said you got the database created. You said you installed XAMPP, With XAMPP comes a tool to admin MySQL called "phpmyadmin" if you use the interface for xampp and select admin MySQL, it will take you to this tool which is much easier for folks new to databases to use.
It is only suggested that you use some form of the app name as the name or in the name of the database you create for it. it makes it easier to identify when it comes time to backup or otherwise administrate it. Typically though, you can use any name, any name for a user and any password as long as those are the information you provide to the web app config file to access the database.
For security reasons, you should ALWAYS set a secure password ( 8 to 12 characters, mixed letters, numbers and symbols) for the root or admin user of the database. for example, mySQL provides user "root" with no password by default, it needs one. same for postgresql, it comes with user 'postgres' and also needs a pass created for it. then you create another user, usually the same name or related. You shouldn't really use the 'root' or primary database admin account for webapps to access the database.
Big Bear