How can I create a Member Page custom sign up with just facebook?

There is a better way, how to share a CODE with other forum-user.
Please use CODE-Tags… like this one here…

<!DOCTYPE html>
<html>
<head>
<title>Facebook Login JavaScript Example</title>
<meta charset="UTF-8">
</head>
<body>

<div id="fb-root"></div>
<script async defer crossorigin="anonymous" src="https://connect.facebook.net/hu_HU/sdk.js#xfbml=1&version=v9.0&appId=MYAPPID&autoLogAppEvents=1" nonce="G5pIT0DK"></script>

<div class="fb-login-button" data-size="large" data-button-type="login_with" data-layout="default" data-auto-logout-link="true" data-use-continue-as="true" data-width=""></div>

<script>
  window.fbAsyncInit = function() {
    FB.init({
      appId      : 'MY APP ID',
      cookie     : true,
      xfbml      : true,
      version    : 'v9.0'
    });
      
    FB.AppEvents.logPageView();   
      
  };

  (function(d, s, id){
     var js, fjs = d.getElementsByTagName(s)[0];
     if (d.getElementById(id)) {return;}
     js = d.createElement(s); js.id = id;
     js.src = "https://connect.facebook.net/en_US/sdk.js";
     fjs.parentNode.insertBefore(js, fjs);
   }(document, 'script', 'facebook-jssdk'));

</script>
</body>
</html>

You will find the CODE-TAGs here…
Also called as “CODE-SNIPET”