How can i use this to send SOAP request and receive response

Question

I just saw this code here: enter link description here and its seems preatty good, but I don't know how to use it. I have to call it from the controller? How can I use the information that it is returned? I am very new with Web Services, so I'm not very sure how to use it.

   public async Task<string> CreateSoapEnvelope()
    {
  string soapString = @"<?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>
              <HelloWorld xmlns=""http://tempuri.org/"" />
          </soap:Body>
      </soap:Envelope>";

      HttpResponseMessage response = await PostXmlRequest("your_url_here", soapString);
      string content = await response.Content.ReadAsStringAsync();

  return content;
  } 

  public static async Task<HttpResponseMessage> PostXmlRequest(string baseUrl, string 
  xmlString)
  {
      using (var httpClient = new HttpClient())
     {
      var httpContent = new StringContent(xmlString, Encoding.UTF8, "text/xml");
      httpContent.Headers.Add("SOAPAction", "http://tempuri.org/HelloWorld");

      return await httpClient.PostAsync(baseUrl, httpContent);
     }
}