Page numbers usually live in the header or footer. These "areas" are properties of the page style.
Considering the way your question is asked, I assume you're a newbie and have typed your short story without "fancy" formatting (all of it being done manually). The result of this is you have a single page style.
Format
>Page Style
to open the dialog to control the parameters - go to the
Header
tab (or the Footer
if you prefer the page number at bottom of the page) - tick the Enable footer check box
OK
For convenience, I recommend you View
>Text Boundaries
and View
>Formatting Marks
so that you cann see how your page is structured. All the cues do not print, so that you can keep this hint always enabled.
Click in the top part of the page, above your text. This will put the cursor in the header.
After the field is inserted, you can format it with text before/after, tabs, ...
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