There are plenty of tutorials online on how to integrate PHP with Facebook, but I think the best place to start is Facebook itself. Their documentation can be a little iffy, but they do have a nice PHP SDK that can be found at https://developers.facebook.com/docs...ence/php/4.0.0

A quick Google search brought up this tutorial which a quick glance reveals to be pretty good:
Wrangling with the Facebook Graph API - Tuts+ Code Tutorial

It'll take you through the steps from creating an App in Facebook to actually coding it (and by App, it can mean almost anything, from just downloading some FB data via their graph API, to integrating logins between your site and FB to creating a full-blown web application).

Something I put together for testing the graph ..

the PHP code tags are not working on the forum, so here it is ugly...

function fetchData($user)
{
if(!empty($user))
{
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://graph.facebook.com/".$user);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_REFERER, "http://www.jpmalloy.com"); // change to your URL
$body = curl_exec($ch); // json string
curl_close($ch);
$data = json_decode($body, true);
return $data;
}
}

$user = ''; // Facebook username
$data = fetchData($user);
echo "https://graph.facebook.com/".$data['id']."/picture?type=large";

Enjoy