I'm horrible with API, so i have a few questions.
Do I have to create a program in order to use API.
if so is it node,js that I use to create an api application, and where do I put it on the server so that APIs can be accessed on my OSSN website. Thank you

Andy, this is basic example of work, you can write your own method to utilize this api.

I worked it out, this is how you do it

<?php
$url= 'https://<insert URL/GQDN here>/api/v1.0/user_details?api_key_token=<insert your API key here>&guid=1';

$arrContextOptions=array(
      "ssl"=>array(
            "verify_peer"=>false,
            "verify_peer_name"=>false,
        ),
    );

$response = file_get_contents($url, false, stream_context_create($arrContextOptions));
echo "<pre>";
print_r($response);
echo "</pre>";
?>

I would like that too.