<?php
    //Data, connection, auth
    $dataFromTheForm = $_POST['fieldName']; // request data from the form
    $soapUrl = "https://connecting.website.com/soap.asmx?op=DoSomething"; // asmx URL of WSDL
    $soapUser = "username";  //  username
    $soapPassword = "password"; // password

    // xml post structure

    $xml_post_string = '<?xml version="1.0" encoding="utf-8"?>
                        <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
                          <soap:Body>
                            <GetItemPrice xmlns="http://connecting.website.com/WSDL_Service"> // xmlns value to be set to your's WSDL URL
                              <PRICE>'.$dataFromTheForm.'</PRICE>
                            </GetItemPrice >
                          </soap:Body>
                        </soap:Envelope>';   // data from the form, e.g. some ID number

       $headers = array(
                    "Content-type: text/xml;charset="utf-8"",
                    "Accept: text/xml",
                    "Cache-Control: no-cache",
                    "Pragma: no-cache",
                    "SOAPAction: http://connecting.website.com/WSDL_Service/GetPrice",
                    "Content-length: ".strlen($xml_post_string),
                ); //SOAPAction: your op URL

        $url = $soapUrl;

        // PHP cURL  for https connection with auth
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_USERPWD, $soapUser.":".$soapPassword); // username and password - declared at the top of the doc
        curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
        curl_setopt($ch, CURLOPT_TIMEOUT, 10);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $xml_post_string); // the SOAP request
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

        // converting
        $response = curl_exec($ch);
        curl_close($ch);

        // converting
        $response1 = str_replace("<soap:Body>","",$response);
        $response2 = str_replace("</soap:Body>","",$response1);

        // convertingc to XML
        $parser = simplexml_load_string($response2);
        // user $parser to get your data out of XML response and to display it.
?>