However, if you want the page numbers to go in the footers, follow the same steps, but any time you see me doing something in the header, do it in the footer instead.

You can add page numbers in Word to the header or footer sections of a document using the page numbers option in the Insert menu.

You can insert or add Header and Footer in Excel spreadsheet using this tutorial. Insert page number, current date and time, etc.

LibreOffice versatile tools allow you to easily add page numbers to the document you are working on: Here's how to paginate in LibreOffice.