File Upload to remote server via HTTPS

Hi All
I am working on a project in which i have to upload files to an remote
server via HTTPS.
For that i have written the following lines of code,but when i execute it I
am getting an
HTTP:500 Internal Server Error.Please let me know where went wrong in it.

1.The client has given the credentials(username & password) using those i
got conneted to the server successfully,but when i run the below code to upload files it is giving me the

HTTP:500 Internal Server Error.
Thanks in advance

Regards
[email protected]

The code is

Try
Dim postdata As String

Dim encoding As New ASCIIEncoding

Dim myWebRequest As HttpWebRequest =
WebRequest.Create(HTTPS_URL)

myWebRequest.Method = "POST"

myHttpWebRequest.ContentType =
"application/x-www-form-urlencoded"

postdata = "file" + Microsoft.VisualBasic.ChrW(61) +
"C:\Documents and Settings\vighneswar\My Documents\My Pictures\vighnesh.jpg"

Dim byte1 As Byte() = encoding.GetBytes(postdata)

myWebRequest.ContentLength = postdata.Length

Dim newStream As Stream = myWebRequest.GetRequestStream()

newStream.Write(byte1, 0, byte1.Length)

newStream.Close()

Dim myWebResponse As WebResponse = myWebRequest.GetResponse()

Dim Rsr As New StreamReader(myResponse.GetResponseStream(),
System.Text.Encoding.Default)

Dim SResponse As String

SResponse = Rsr.ReadToEnd()

MsgBox(SResponse)

Catch ex As WebException

If ex.Status = WebExceptionStatus.ProtocolError Then

Dim myWebResponse As HttpWebResponse = ex.Response

MsgBox(mywebresponse.StatusDescription)

End Try