just watch a youtube video - seriously
(https://www.youtube.com/watch?v=jLqBiSDNXO0 - good for setup)
Download XAMPP here.
https://www.apachefriends.org/download.html
after setup load 'XAMPP control panel' app.
click start for Apache and Mysql.
put your code in xampp htdocs folder,
load it by going to localhost in browser.
create database by going to http://localhost/phpmyadmin/ in browser.
watch youtube videos etc for more help;)
e.g. https://www.youtube.com/watch?v=WmFHreVid-k -
Connect to MySQL with PHP in XAMPP / Create a new database

$connection = mysqli_connect($server_name, $user_name, $password);