Using mysqli_connect()

[sorcerer stone]

My OS is Win10 (with latest update).
I installed manually Apache, MySQL, PHP (with default settings for each packages).
I have imported a database using MySQL command line. The database is located in the default directory: "C:\ProgramData\MySQL\MySQL Server 8.0\Data".
MySQL placed this database and all its tables inside a folder that bears the name of the database eg. MyTestDB.

I am learning how to query database in a php file. However, most of the examples I see in YouTube used the WAMP or XAMP setups where all individual modules are connected during install. So, in these setups, one can query MySQL database using the followings:

<?php
$servername = "localhost";
$database = "database";
$username = "username";
$password = "password";
// Create connection
$conn = mysqli_connect($servername, $username, $password, $database);
...

In my case, where I manually installed these component, how do I tell in my php script

1/ where MySQL is located on my laptop
2/ which directory the database is located? is it something like $database = "C:\ProgramData\MySQL\MySQL Server 8.0\Data\MyTestDB"
3/ How to modify the above mysqli_connect() statement in order to fit my setup for connecting to my database (MyTestDB)?
4/ Do I need additional statement(s) to connect to the MySQL engine on my laptop?

Thanks in advance.
Sorcerer