Hi everyone I'm new in wordpress development. I have difficulty cause my Registration page is no password input but there's automatic password given every register. So I would like to get the password of what I register. I'll give you the image. 
And I would like to get the value of username to put in my own php file. How to do it ?
Yes, you should include your php file in functions.php in WordPress theme folder.
In functions.php : require( 'your_php_file' );
And write :
<?php
add_action( 'init', 'fetch_login_form');
function fetch_login_form() {
$user_email = $_POST['user_email'];
// write condition based on Username or User email.
}
Password is autogenerated while we receive an email so you can stop send email and allow user to register directly. Follow this link : How to disable wordpress confirmation email for new users
