consume java web api that needs client certificate in .net

Hi every body,

we use .NET framework ( website ,windows forms) in our company , I need to consume a wep api from another company which is built using java, and they need to authenticate the client using certificates 

the company API interface is simple, they use a REST technology over https with JSON data exchange, the asked to send Exchange certificate:  "We need you to send us a public key of your SSL certificate.  If you don't have a commercial one, you can issue a self signed one (Note: if you use java you can use the 'keytool' utility). Then we will install your certificate as a trusted peer so that we accept requests from you."

I send them a public key for a self signed certificate generated from IIS (X.509base 64 encoded), and they send me a sample java code for API CALL

package com.bisan.proj.act;

import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.URL;
import java.security.KeyStore;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import com.google.gson.Gson;

public class ApiTest_currency {

  private static final String myKeyStore = ""; //TODO this is your private key store.
  private static final String myKeyPass = "";//TODO keystore password

  private static final String account = ""; //TODO bisan account
  private static final String user = ""; //TODO user
  private static final String password = ""; //TODO password

  private static SSLSocketFactory sslFactory = null;

  private static SSLSocketFactory getFactory() throws Exception {
    if (sslFactory == null) {
      KeyStore clientKeyStore = KeyStore.getInstance(KeyStore.getDefaultType());
      clientKeyStore.load(new FileInputStream(myKeyStore),
          myKeyPass.toCharArray());
      KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory
          .getDefaultAlgorithm());
      kmf.init(clientKeyStore, myKeyPass.toCharArray());
      SSLContext ctx = SSLContext.getInstance("TLS");
      ctx.init(kmf.getKeyManagers(), null, null);
      sslFactory = ctx.getSocketFactory();
    }
    return sslFactory;
  }//getFactory

  public static void main(String[] args) throws Exception {
    System.out.println(createRequest());
    URL url = new URL("https://gw.bisan.com/api/" + account);
    HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
    connection.setSSLSocketFactory(getFactory());
    connection.setRequestProperty("Content-Type", "application/json");
    connection.setDoInput(true);
    connection.setDoOutput(true);

    //set the request
    OutputStream out = connection.getOutputStream();
    out.write(createRequest().getBytes());
    out.close();
    int status = connection.getResponseCode();
    System.out.println(status + " " + connection.getResponseMessage());
    if (status == 200)
      handleResponse(connection.getInputStream());
  }//main
  /* JSON Request
   * {  
   *    "user"      : "test", 
   *    "password"  : "12345",
   *    "command"   : "table",
   *    "table"     : "currency",
   *    "filters"   : [ {"field"    : "code",
   *                     "operation": "!=",
   *                     "value"    : "01" }
   *                  ],
   * 
   *    "fields"    : ["symbol", "rate"]
   * }
   *
   */
  private static String createRequest() {
    Map<String, Object> request = new HashMap<String, Object>();
    request.put("user", user);
    request.put("password", password);
    request.put("command", "table");
    request.put("table", "currency");

    ArrayList filters = new ArrayList();
    Map f1 = new HashMap();
    f1.put("field", "code");
    f1.put("operation", "!=");
    f1.put("value", "01");
    filters.add(f1);
    request.put("filters", filters);

    ArrayList fields = new ArrayList();
//    fields.add("code");
//    fields.add("name");
    fields.add("symbol");
    fields.add("rate");
    request.put("fields", fields);

    Gson gson = new Gson();
    return gson.toJson(request);
  }//createRequest
  
  
  /* JSON Reply
   * {
   *    "command" : "table",
   *    "table"   : "currency",
   *    "error"   : "",
   *    "filters" : [ { "field"     : "code", 
   *                    "operation" : "!=",
   *                    "value"     : "01" }
   *                ],
   * 
   *    "fields"  : [ "symbol", "rate"],
   * 
   *    "rows":   [ {"symbol":"USD" ,"rate":"3.86000"},
   *                {"symbol":"JD"  ,"rate":"5.41000"},
   *                {"symbol":"4"   ,"rate":"0.70900"}
   *              ]
   * }
   *
   */
  private static void handleResponse(InputStream in) {
    Gson gson = new Gson();
    Map reply = gson.fromJson(new InputStreamReader(in), Map.class);
    System.out.println("\nerror: " + reply.get("error"));
    if (reply.get("error") != null)
      return;
    List<Map> rows = (List<Map>) reply.get("rows");
    System.out.println("rows " + rows.size());
    for (Map m : rows) 
      System.out.println(m.get("symbol") + " " + m.get("rate"));
  }//handleResponse
}//class

I served the net to find the equivalent code for sending Client Request with Certificate in .NET but I get lost in articles, I can't distinguish between X509Certificate and X509Certificate2 which one to use and the path of my private key, should I only provide the path, or locate it from the store (MMC) 

my code Trial 

using System;
using System.Net;
using System.Security.Cryptography.X509Certificates;

class Program
{
    class MyWebClient : WebClient
    {

        // private ssl key info
        string myKeyStore = @"C:Key.pfx";
        string myKeyPass = ""; //password
       protected override WebRequest GetWebRequest(Uri address)
        {
            HttpWebRequest request = (HttpWebRequest)base.GetWebRequest(address);
            X509Certificate cert2 = new X509Certificate(myKeyStore, myKeyPass);
            request.ClientCertificates.Add(cert2);
            return request;
        }
    }
    static void Main(string[] args) 

        {
        // Bisan Demo Account
        string account = "";
        string user = "";
        string Bisanpassword = "";

        var client = new MyWebClient();    
        var data = client.DownloadString("https://gw.bisan.com/api/" + account);
        Console.WriteLine(data);
        }
    }

but this didn't work 

any help please