C# and VC6 Web Services File Upload

I'm cross posting, sorry, but this pertains to both sides..

I have a Web Services written in C# and a client written in VC6. I've
never uploaded files through web services so forgive my ignorance in this
matter, but I'm trying to understand how I can do this from the C++ client.

The C# code works for HTTP Form Posts, but not really what I'm looking for..
This should be for applications to upload files too.. The code is as
follows:
-----------------------------------------------------------------
[WebMethod]
public bool UploadFileCollection()
{
  try
  {
    //HTTP Context to get access to the submitted data
    HttpContext postedContext = HttpContext.Current;

    //File Collection that was submitted with posted data
    HttpFileCollection Files = postedContext.Request.Files;

    //Make sure a file was posted
    //This works for HTTP Form Posts, need to understand how to make this
work for C++ posts
    string fileName = (string)postedContext.Request.Form["fileName"];

    if (Files.Count == 1 && Files[0].ContentLength > 1 && fileName != null
&& fileName != "")
    {
      //The byte array we'll use to write the file with
      byte[] binaryWriteArray = new
      byte[Files[0].InputStream.Length];
      //Read in the file from the InputStream
      Files[0].InputStream.Read(binaryWriteArray, 0,
      (int)Files[0].InputStream.Length);
      //Open the file stream
      FileStream objfilestream = new FileStream("c:\\" + fileName,
FileMode.Create, FileAccess.ReadWrite);
      //Write the file and close it
      objfilestream.Write(binaryWriteArray, 0,
      binaryWriteArray.Length);
      objfilestream.Close();
      return true;
    }
    else
    {
      return false;
    }
  }
  catch (Exception ex1)
  {
    throw new Exception("Problem uploading file: " + ex1.Message);
  }
}

-----------------------------------------------------------------

I have VC6 client that is to upload a file to the C# Web Services Interface
using WinHttp..
WinHttpOpen
WinHttpConnect
WinHttpOpenRequest
WinHttpSetOption
WinHttpAddRequestHeaders
WinHttpWriteData //header
WinHttpWriteData //binary file in data chunks
WinHttpWriteData //footer
WinHttpReceiveResponse
WinHttpQueryHeaders
WinHttpQueryDataAvailable
WinHttpReadData
WinHttpCloseHandle

I've never written anything in C++ to talk to Web Services before and I know
this code work for file uploads to IIS via ASPUpload object on the server.
I may be way off, but my searching is leading me no where.