include 'vendor/autoload.php'; use User\User; $user = new User(); $email = $_POST['email']; $password = $_POST['password']; if ($user->authenticate($email, $password)) { // User is authenticated } else { // Invalid email or password }In the above example, we create an instance of the `User` class and call its `authenticate()` method with the email address and password provided by the user from a web form. The `authenticate()` method returns `true` if the email and password combination is valid, and `false` otherwise. The `vendor/autoload.php` file is included at the beginning of the code snippet, which is a standard approach for loading any additional libraries or packages required by the application. It is likely that the User app is using some external libraries or packages to handle other functionality as well.