Asp.net mvc 如何在asp.net mvc中将带有webclient的文件传递给webservice？

我想使用webclient将文件从控制器传递到web服务。如何将文件作为多部分/表单数据传递

    [HttpPost]
    public ActionResult Create(CreateSliders create, HttpPostedFileBase imgUp)
    {
        if (ModelState.IsValid)
        {

            WebClient webclient = new WebClient();
            webclient.Headers[HttpRequestHeader.ContentType] = "application/json;charset=utf-8";
            string url = "MYURL";
            webclient.Headers["Authorization"] = "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes("Username:Password"));
            webclient.Headers.Add("Request-type", "edit-sliders");
            webclient.Encoding = UTF8Encoding.UTF8;
            ///What should i do for pass myfile??

        }

        return View();
    }