Clickbank API - confirming that order has been successful?

Question

I am new to API's and cURL (sorry).

I am looking to use Clickbank's API to check if an order has been successful - https://api.clickbank.com/rest/1.3/orders2

I understand that what I have here is a basic curl request:

define('CLICKBANK_DEV_KEY','DEV-KEY');
define('CLICKBANK_API_KEY','API-KEY');

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://api.clickbank.com/rest/1.3/orders/list");
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Accept: application/json", "Authorization:".CLICKBANK_DEV_KEY.":".CLICKBANK_API_KEY));

$result = curl_exec($ch);

curl_close($ch);

print $result;

How would I use their API to check if an order is successful?

Any tips or resources are appreciated, thank-you.