Curl login authentication cookie issues

<?php

//create array of data to be posted
  $post_data['username_here'] = "username";
  $post_data['password_here'] = "password";
  
  //traverse array and prepare data for posting (key1=value1)
  foreach ( $post_data as $key => $value) {
   $post_items[] = $key . '=' . $value;
  }
 
  //create the final string to be posted using implode()
  $post_string = implode ('&', $post_items);
  $post_string = "dest=%2".$post_string ."&submit=next";
  //i.e. ?dest=%2F&username=username_here&password=password_here&submit=next
  

  //create cURL connection  
  $curl_connection = curl_init("https://my.netspace.net.au/logincheck");
  
  //set options
  curl_setopt($curl_connection, CURLOPT_CONNECTTIMEOUT, 30); //set time untill cURL times out
  curl_setopt($curl_connection, CURLOPT_USERAGENT, 
    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)"); // set HTTP User Agent
  curl_setopt($curl_connection, CURLOPT_HEADER,1);
  curl_setopt($curl_connection, CURLOPT_POST, 1);
  curl_setopt($curl_connection, CURLOPT_POSTFIELDS, $post_string);//set data to be posted
  curl_setopt($curl_connection, CURLOPT_RETURNTRANSFER, true);
  curl_setopt($curl_connection, CURLOPT_FOLLOWLOCATION, 1); // follow redirection if any...
  curl_setopt($curl_connection, CURLOPT_SSL_VERIFYPEER, false); //determin if to continue processing code if SSL certificate is verifyed or not...
  
  //cookie code ive found that dont seem to work...
  /*curl_setopt($curl_connection, CURLOPT_COOKIEFILE, "cookies.txt");
  curl_setopt($ch, CURLOPT_COOKIE, "cookies.txt");
  curl_setopt($curl_connection, CURLOPT_COOKIEJAR, "cookies.txt");
  curl_setopt($curl_connection, CURLOPT_COOKIESESSION, true); //return cookies that cURL collects*/
     
  //perform our request (execute request)
  $result = curl_exec($curl_connection);
  curl_close();
  echo $result;
?>