How to get user data from Facebook Graph Api using php sdk? -

i trying data facebook graph api. don't know how get. following basic tutorial getting trouble. below code in trying see basic object items hese nothing. like

require 'facebook-sdk-2/facebook.php'; $app_apikey =   'xxxx'; $app_secret =   'xxxxxxxxxx';   $facebook =     new facebook($app_apikey, $app_secret);  var_dump($facebook); //returns object items   var_dump($facebook->getuser()); //returns null  

i further user events moreover.

results

  var_dump($facebook); //returns object items object(facebook)[1]   protected 'sharedsessionid' => null   protected 'appid' => string '2' (length=1)   protected 'appsecret' => string '2' (length=1)   protected 'user' => null   protected 'signedrequest' => null   protected 'state' => null   protected 'accesstoken' => null   protected 'fileuploadsupport' => boolean false   protected 'trustforwarded' => boolean false  var_dump($facebook->getuser()); //returns null  int 0 

i think haven't login application, yet.