To make a Firebase database private, you can follow these technical steps:

* Enable Firebase Authentication: Firebase Authentication allows you to authenticate users and control access to your database. You can use Firebase Authentication to authenticate users using various providers, such as email and password, Google, Facebook, and more.

* Configure Firebase Security Rules: Firebase Security Rules allow you to define how your data should be accessed and which users can read or write to the database. You can define rules based on user authentication and specific data paths in the database.