Для ввода файла:
<td><input id= "UploadedFile"  type= "file"  runat= "server"  maxlength= "255 " size= "60 " enctype= "multipart/form-data" ></td>

Это для сохранения:
....
  Public UploadedFile As HtmlInputFile
....
 обработка тправки файла
    Dim filePath As String =  ""
    If Not UploadedFile.PostedFile Is Nothing Then
      filePath = Path.GetFileName(UploadedFile.PostedFile.FileName)
      If Len(filePath) > 0  Then
        Try
          UploadedFile.PostedFile.SaveAs("C:\FileUpload\" & filePath)
        Catch ex As Exception
          Dim errorlog As New ErrorLog(Context)
          errorlog.WriteError(ex)
        End Try
      End If
    End If