Convert command cURL to PHP cURL - php

Question

I've never done any curl before so am in need of some help. I've tried to work this out from examples but cannot get my head around it!
How can I translate this curl command so that it works in a PHP script?
curl -v -H "Content-Type: text/xml" --cert WST279925._.1.pem --key WST279925._.1.key --pass fryeBu23^< -u WST279925._.1:KaWwNI31=$ --url https://test.ipg-online.com/ipgapi/services -d #request.xml --trace-ascii "trace.log" -o "response.xml" --insecure
My code:
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://test.ipg-online.com/ipgapi/services');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POST, 1);
$post = array(
'file' => '#' .realpath('request.xml')
);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
curl_setopt($ch, CURLOPT_USERPWD, 'WST279925._.1' . ':' . $_ENV["KaWwNI31="]);
$headers = array();
$headers[] = 'Content-Type: text/xml';
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
$result = curl_exec($ch);
if (curl_errno($ch)) {
echo 'Error:' . curl_error($ch);
}
curl_close($ch);
how do i add digital certificate and key?
Thanks for any help.