Append existing word doc

Hi ,
I have a word doc with one image in this and I am trying to append that doc file from my aspx web page. but its not getting append the file. Following is the cod i am using to append the document file.
Dim strP as string = Server.MapPath("~/Test.doc") Dim fs1 As FileStream = New FileStream(strP, FileMode.Append, FileAccess.Write) Dim info As Byte() = New UTF8Encoding(True).GetBytes(objLiteral.ToString()) fs1.Write(info, 0, info.Length) info = New UTF8Encoding(True).GetBytes("<img Src = '" + imagename + "'></img></body></html>") fs1.Write(info, 0, info.Length) fs1.Close() Can anyone please help me