One function in c# to add to a text editor project

Add or remove pages to the editor: when you start the program you have a blank page, when this arrives certain lines (25) must create the next page (RichTextBox) and the cursor must jump to this, and vice versa when characters are deleted, practically what happens in Microsoft word, the count of lines event is already developed only needs the function to add or remove page. private void rtbEditor_TextChanged(object sender, TextChangedEventArgs e) { //n pages * 25 = number lines to event var textRange = new TextRange([login to view URL], [login to view URL]); if (Lines([login to view URL]) >25) { [login to view URL](Lines([login to view URL])); } }