How to upload image to server on HTTP POST without namespace of System?

Hello

I am developing Windows Store App now.

I need to upload image file to Azure Server as Multipart-Content.

I converted each data (fx, header , image file) to byte[] data.

And I combined each byte[] data into one.

here is my code,but it don't work.

async private void ProfileImage_doubleTapped(object sender, DoubleTappedRoutedEventArgs e)
        {
            FileOpenPicker openPicker = new FileOpenPicker();
            
            openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
            
            openPicker.ViewMode = PickerViewMode.Thumbnail;
            
            openPicker.FileTypeFilter.Clear();
            openPicker.FileTypeFilter.Add(".bmp");
            openPicker.FileTypeFilter.Add(".png");
            openPicker.FileTypeFilter.Add(".jpeg");
            
            StorageFile file = await openPicker.PickSingleFileAsync();
            fileName = file.Name;
            
            if(file != null)
            {
                
                filestream = await file.OpenAsync(FileAccessMode.Read);
                
                bitmapImage = new BitmapImage();
                bitmapImage.SetSource(filestream);
                
                if(bitmapImage.PixelHeight >64 && bitmapImage.PixelWidth > 64)
                {
                    return;
                }
                profileimage.Source = bitmapImage;

                Uri targetAdresse = new Uri("http://ift.tt/MQsb2s;);
                
                
                HttpCookie cookie = new HttpCookie("sid", domainValue, "");
                cookie.Value = sidValue;
                cookie.Secure = false;
                cookie.HttpOnly = false;
                HttpBaseProtocolFilter filter = new HttpBaseProtocolFilter();
                var replaced = filter.CookieManager.SetCookie(cookie, false);

                string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
                byte[] boundaryByte = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");
                BasicProperties bp = await file.GetBasicPropertiesAsync();
                string formDataTemplate = "name = \"{0}\"\r\n\r\n{1}";
                string headerTemplate = "name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
                string header = string.Format(headerTemplate, "prfimg", fileName, file.ContentType);
                string formItem = string.Format(formDataTemplate, "prfimg", file);
                byte[] fdata = new byte[bp.Size];
                byte[] headerByte = System.Text.Encoding.UTF8.GetBytes(header);
                byte[] formItemByte = System.Text.Encoding.UTF8.GetBytes(formItem);
                byte[] trailer = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");

                IInputStream istream = filestream.GetInputStreamAt(0);
                DataReader reader = new DataReader(istream);
                await reader.LoadAsync((uint)fdata.Length);
                reader.ReadBytes(fdata);
                

                byte[] data = new byte[headerByte.Length + fdata.Length];
                Array.Copy(headerByte, 0, data,0, headerByte.Length);
                Array.Copy(fdata, 0, data,headerByte.Length, fdata.Length);

                MemoryStream mem = new MemoryStream(data);
                IInputStream rstream = mem.AsInputStream();


                HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Post, targetAdresse);
                HttpMultipartFormDataContent content = new HttpMultipartFormDataContent(boundary);
                HttpStreamContent stream = new HttpStreamContent(rstream);
                content.Add(stream);
                requestMessage.Content = content;

                HttpResponseMessage response;
                HttpClient client = new HttpClient();
                response = await client.SendRequestAsync(requestMessage);
                profileText.Text = await response.Content.ReadAsStringAsync();
            }
              
        }

I want some advice.