PHP Code:
<html>
<head>
<title>My Facebook Login Page</title>
</head>
<body>
<div id='fb-root'></div>
<script src='http://connect.facebook.net/en_US/all.js'></script>
<script>
FB.init({
appId:'YOUR_APP_ID', cookie:true,
status:true, xfbml:true
});
</script>
<fb:login-button>Login with Facebook</fb:login-button>
</body>
</html>
Ull need an app id, u can get one if ur a verified user..
to verify u gotta add ya mobile number to there site
enjoy