check.php

<?php
include ('Connect.php');

$test = new Connect;
$test->createUser();

?>

Connect.php

<?php

class Connect {
    private $connection;

    public function __construct(){
        $this->connect();
    }

    public function connect(){
        $this->connection = new PDO('mysql:host=orfarile;dbname=orfarile', 'root', '');
    }

    function selectTests(){
        
    }

    public function createUser(){
        $this->connection->query("INSERT INTO users(user_login, user_password) VALUES ('test1', 'test1')");
    }
}

?>