How to Post data in C# . NET HttpWebRequest

For post data to PHP in C# I use this method:

        public string Post(string url, string data) {
       

           string vystup = null;
           try
           {
               //Our postvars
               byte[] buffer = Encoding.ASCII.GetBytes(data);
               //Initialisation, we use localhost, change if appliable
               HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create(url);
               //Our method is post, otherwise the buffer (postvars) would be useless
               WebReq.Method = "POST";
               //We use form contentType, for the postvars.
               WebReq.ContentType = "application/x-www-form-urlencoded";
               //The length of the buffer (postvars) is used as contentlength.
               WebReq.ContentLength = buffer.Length;
               //We open a stream for writing the postvars
               Stream PostData = WebReq.GetRequestStream();
               //Now we write, and afterwards, we close. Closing is always important!
               PostData.Write(buffer, 0, buffer.Length);
               PostData.Close();
               //Get the response handle, we have no true response yet!
               HttpWebResponse WebResp = (HttpWebResponse)WebReq.GetResponse();
               //Let's show some information about the response
               Console.WriteLine(WebResp.StatusCode);
               Console.WriteLine(WebResp.Server);

               //Now, we read the response (the string), and output it.
               Stream Answer = WebResp.GetResponseStream();
               StreamReader _Answer = new StreamReader(Answer);
               vystup =  _Answer.ReadToEnd();

               //Congratulations, you just requested your first POST page, you
               //can now start logging into most login forms, with your application
               //Or other examples.
           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.Message);
           }
           return vystup.Trim()+"\n";
       
        }