facebook login button integration

Hi all
So I have a website to which I have added a facebook login button. the button itself works like a charm. However, I can't figure out how I can check, if the user is now logged in, so I only show the content to logged in users. Dows FB set a cookie upon loggin in, or how can I check for it?
I also would like to pull the data about the user from facebook. i'm thinking I need to access the Graph API, but I'm not that proficient in programming, and cant seem to understand how it's done.
Can someone please help me?
thanks

 

Are you using the php SDK ?

 

You can also check facebook's new developer forum @ facebook.stackoverflow.com

 

hot to do this i need to get that

 

Thanks for your reply
Oddly enough, I can't seem to find any documentation about how to see, if the user has logged in. It's easy enough to implement the login button, but I need to be able to access a cookie or something. Othewise it's no use...

 

Here's a snippet from a fb application. For websites, procedure is same.

Change a few things link canvasurl,fbconnect=1,canvas=0 etc.

<?php
session_start();
ob_start();
require_once("facebook.php"); // including the SDK
$thispage = 'http://example.com/myfbAPP/index.php';
$canvasurl = 'http://apps.facebook.com/myfbAPP/';
$fb = new Facebook(array('appId'  => 'APP_ID','secret' => 'APP_SECRET','cookie' => true,));
$perms = 'publish_stream,user_photos';
$user = $fb->getUser();
if(is_null($user)  || $user==0){
   $loginurl = $fb->getLoginUrl(array('canvas'=>1,'fbconnect'=>0,'display'=>'page','redirect_uri'=>$canvasurl,'scope'=>$perms));
   echo"<script type='text/javascript'>top.location=\"$loginurl\";</script>";
   exit;
}
else{
    $userinfo = $fb->api("/$user");
    echo"
    <br />
    <img src='http://graph.facebook.com/$user/picture/?type=square' alt='' />
    <a class='fbxWelcomeBoxName' href='$userinfo[link]'>$userinfo[name]</a>
    <br/>
    ";


// YOUR POST LOGIN STUFF GOES HERE 
?>

Code (markup):

 

Got it working now.
Thanks to Technoslab. It got me on the right track.