how to assign api key in asp.net webform ?

Hi guys,

how to assign api key in asp.net webform ? 

i would like to call rest api value from this url "https://api.rajaongkir.com/starter/province?id=12"

to call api value i must assign API key from my codebehind, how to add api key in my codebehind ?

i just get tutorial in php version, how to in asp.net ? 

this is code api key if using PHP.

<?php$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => "https://api.rajaongkir.com/starter/province?id=12",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => array("key: your-api-key"
  ),
));$response = curl_exec($curl);$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

?>

Thank you & Regards.
Wibowo Wiwit