How to create GA event for New Registration in “user_register” WordPress hook?

So basically On My WordPress site I have 3 different ways to register (std Reg. Form, Social Media Plugin, Membership Reg.) this way I am tracking new user registration through “user_register” WordPress hook and sending notification by email to CEO,

add_action( 'user_register', 'new_registration_email_notification', 10, 1 );

function new_registration_email_notification( $user_id )
{
    global $current_user;

    wp_mail( $multiple_recipients, $subject, $body, $headers );
}

In addition I need to add Google Analytics event in “user_register” hook in order to “catch” all 3 registration ways, I have already understood from here that it supposed to be GA client written in PHP but I don’t really see that it will do the work like std GA javascript.

var Register= document.getElementById("Register");          
Register.onclick = function() {
    ga('send', 'event', 'Register', 'Click/Touch');

Didn’t find much info about it, so if somebody could help with some explanation it would be great.