Thank you Zephni,
this is my code:
$app_id = "xxxxxxxxxxxx";
$app_secret = "xxxxxxxxxxxxxxxxx";
include_once 'facebook.php';
global $api_id,$app_secret;
$facebook=new facebook($api_id,$app_secret);
$uid = $facebook->getUser();
echo $uid;
but this error are in error_log:
[02-Dec-2011 15:20:11] PHP Fatal error: Call to a member function getUser() on a non-object in /home/mintcom/public_html/apps/arena/camara/hola.php on line 10
this is my link
http://mint.com.sv/apps/arena/camara/hola.php
I dont know what are doing wrong...