How can I set or specify the number of pages to be print?

I created a richtextbox to input the text that I want to print, the command for printing which is the button and instead of printdialog box((PrintDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK)) to be display, I created combobox which will display the available printers and then print.  Like this code bellow .

To get the available printers:

    foreach (String printer in PrinterSettings.InstalledPrinters)
            {
                        cbox.Items.Add(printer.ToString());
            }

And the button for printing :

 PrintDocument1.PrinterSettings.PrinterName = cbox.SelectedItem.ToString();

PrintDocument1.Print();