contact-form.php

/**
$posted_data = PHP array consisting posted data from the form :
$posted_data = array(
  'message' => '',
  'fullname' => '',
  'company' => '',
  'position' => '',
  'telephone' => '',
  'email' => ''
);
*/

    $action_url = 'https://webto.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8';
    $formdata = 'lead_source=Web-ID&Campaign_ID=7015F000000hgGK&description='. $posted_data['message'] .'&last_name='. $posted_data['fullname'] .'&first_name=&company='. $posted_data['company'] .'&title='. $posted_data['position'] .'&phone='. $posted_data['telephone'] .'&email=' . $posted_data['email'];
    $ch = curl_init($action_url);
    curl_setopt( $ch, CURLOPT_POST, 1);
    curl_setopt( $ch, CURLOPT_POSTFIELDS, $formdata);
    curl_setopt( $ch, CURLOPT_FOLLOWLOCATION, 1);
    curl_setopt( $ch, CURLOPT_HEADER, 0);
    curl_setopt( $ch, CURLOPT_RETURNTRANSFER, 1);
    curl_exec( $ch );