POST xsd schema using C sharp is it similar like XML POST?

<xs:complexType>
 <xs:sequence>
  <xs:element type="Source" name="Source"/>
   <xs:element type="AgentId" name="AgentId" minOccurs="0"/>
   <xs:element type="Password" name="Password" minOccurs="0"/>
   <xs:element type="SessionId" name="SessionId"/>
   <xs:element type="ClearBasket" name="ClearBasket" minOccurs="0"/>
   <xs:element type="ItemReference" name="ItemRef"/>
   <xs:element type="Item" name="OutAvail"/>
  <xs:element type="Item" name="InbAvail" minOccurs="0"/>
 </xs:sequence>
</xs:complexType>

<Request>
   <FlightSearch>
   <Source>0</Source>
   <AgentId>0</AgentId>
   <Password>0=</Password>
    <From>lhr</From>
    <To>lhe</To>
    <RetFrom />
    <RetTo />
    <Journey>R</Journey>
    <Direct />
    <Availability>O</Availability>
   </FlightSearch>
 </Request>

  public string postXMLData(string destinationUrl, XDocument requestXml)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(destinationUrl);
            byte[] bytes;
            bytes = Encoding.UTF8.GetBytes(requestXml.ToString());
            request.ContentType = "text/xml";
            request.ContentLength = bytes.Length;
            request.Method = "POST";
            Stream requestStream = request.GetRequestStream();
            requestStream.Write(bytes, 0, bytes.Length);
            requestStream.Close();
            HttpWebResponse response;
            response = (HttpWebResponse)request.GetResponse();
if (response.StatusCode == HttpStatusCode.OK)
            {
                Stream responseStream = response.GetResponseStream();
                string responseStr = new StreamReader(responseStream).ReadToEnd();
             }

         }