$post_data = array(
"end" => array("dateTime" => "2013-14-11T10:40:00.000-07:00"),
"start" => array("dateTime" => "2013-14-11T10:00:00.000-07:00"),
"summary" => "my_summary",
"description" => "my_description"
);
$post_data = json_encode($post_data);
curl_setopt($ch2, CURLOPT_HTTPHEADER, array(
'Content-Type: application/json',
'Content-Length: ' . strlen($post_data),)
);