using System;

using System.Net;

using System.Text;  // for class Encoding

using System.IO;    // for StreamReader

public class Program

{

    public static void Main()

    {

        var request = (HttpWebRequest)WebRequest.Create("https://api.upayments.com/test-payment");

​

        var postData = "merchant_id=" + Uri.EscapeDataString("1201");

            postData += "&username=" + Uri.EscapeDataString("test");

            postData += "&password=" + Uri.EscapeDataString("test");

            postData += "&api_key=" + Uri.EscapeDataString("jtest123");

            postData += "&order_id=" + Uri.EscapeDataString("188411414141414");

            postData += "&total_price=" + Uri.EscapeDataString("1");

            postData += "&success_url=" + Uri.EscapeDataString("http://example.com/success.html");

            postData += "&error_url=" + Uri.EscapeDataString("http://example.com/error.html");

        var data = Encoding.ASCII.GetBytes(postData);

​

        request.Method = "POST";

        request.ContentType = "application/x-www-form-urlencoded";

        request.ContentLength = data.Length;

​

        using (var stream = request.GetRequestStream())

        {

            stream.Write(data, 0, data.Length);

        }

​

        var response = (HttpWebResponse)request.GetResponse();

​

        var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();

        Console.WriteLine(responseString);

    }

}