PHP coding to incorporate Oodle listings

i'm trying to add Oodle listings to my websites using their API code and i really don't have a clue as to how to do it.. I was told to code the following:

<?php
$data = simplexml_load_file('http://api.oodle.com/api/v2/listings?key=KEYVALUE&region=usa&category=vehicle/car&format=xml&attributes=make_ford,model_mustang');

foreach($data->listings as $listing) {
print $listing->title;
}
?>

but it doesn't work - doesn't even interpret the php code and is not shown when you do a 'view source' from the webpage..

can anyone help me here?

Thanks