At its simplest, plain ("vanilla") text is entered into the text block as shown below. Text may be typed in, or pasted from other applications (e.g. Microsoft Word).

N.B. if you paste text which contains enhancements (e.g. bold, italic, font changes, etc) from Microsoft Word, these enhancements will also be pasted into the text area.
The Page Preview panel below the text area may be used to get an impression of the final appearance of the page without committing your changes. Just press the Update Preview button.