the line of code that is causing the prob pingpressfm/pingPressFM2.php on line 493

I downloaded the pingpress plugin from wordpress.org - I entered my API Key in the option but when I turn the plug in on I get

Fatal error: Call to undefined function curl_init() in

function pingpressfm2_verify() {
// do the deed with ping.fm
$ch = curl_init(); ----> (LINE 493)
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_URL, 'http://api.ping.fm/v1/user.validate');
curl_setopt($ch, CURLOPT_POSTFIELDS, Array('api_key' => get_option('pingpressfm2_api_dev'), 'user_app_key' => get_option('pingpressfm2_api_user')));
$output = curl_exec($ch);