rich text editor in WPF and C# which can open and save html format file

void CmdNew(object sender, RoutedEventArgs e)
       {
           txtcreatelssn.Document = new FlowDocument();
       }
       void Open1(object sender, RoutedEventArgs e)
       {
           System.Windows.Forms.OpenFileDialog openFile = new System.Windows.Forms.OpenFileDialog();
           openFile.Filter = "XAML Files (*.xaml)|*.xaml|RichText Files (*.rtf)|*.rtf|All Files (*.*)|*.*";

           if (openFile.ShowDialog() == System.Windows.Forms.DialogResult.OK)
           {
               // Create a TextRange around the entire document.
               TextRange documentTextRange = new TextRange(txtcreatelssn.Document.ContentStart, txtcreatelssn.Document.ContentEnd);

               using (FileStream fs = File.Open(openFile.FileName, FileMode.Open))
               {
                   if (System.IO.Path.GetExtension(openFile.FileName).ToLower() == ".rtf")
                   {
                       documentTextRange.Load(fs, System.Windows.DataFormats.Rtf);
                   }
                   else
                   {
                       documentTextRange.Load(fs, System.Windows.DataFormats.Xaml);
                   }
               }

           }
       }

       void save1(object sender, RoutedEventArgs e)
       {
           System.Windows.Forms.SaveFileDialog savefile = new System.Windows.Forms.SaveFileDialog();
           //System.Windows.Forms.OpenFileDialog openFile = new System.Windows.Forms.OpenFileDialog();
           savefile.Filter = "XAML Files (*.xaml)|*.xaml|RichText Files (*.rtf)|*.rtf|All Files (*.*)|*.*";

           if (savefile.ShowDialog() == System.Windows.Forms.DialogResult.OK)
           {
               // Create a TextRange around the entire document.
               TextRange documentTextRange = new TextRange(
                   txtcreatelssn.Document.ContentStart, txtcreatelssn.Document.ContentEnd);
               MemoryStream ms = new MemoryStream();
               // If this file exists, it's overwritten.
               using (FileStream fs = File.Create(savefile.FileName))
               {
                   if (System.IO.Path.GetExtension(savefile.FileName).ToLower() == ".rtf")
                   {
                       documentTextRange.Save(fs,System.Windows.DataFormats.Rtf);
                   }
                   else
                   {
                       documentTextRange.Save(fs, System.Windows.DataFormats.Xaml);

                   }
               }

           }

       }