Include the SOAP Client

<?php require_once('SOAP/Client.php'); ?>
Generate the Client Proxy

<?php
$wsdlurl = 'http://api.google.com/GoogleSearch.wsdl';
$WSDL =& new SOAP_WSDL($wsdlurl);
$client =& $WSDL->getProxy();
?>
Make the SOAP Call

<?php
$response =
        $client->doGoogleSearch(
                    $key,$query,0,4,
                    false,'',false,'','','');
?>
Do something with the results

<?php
foreach($response->resultElements as $result) {
    echo '<a href="'.$result->URL.'">';
    echo $result->title."</a><br><br>\n";
    echo $result->snippet."<br><br><br>\n";
}
?>