How to add GPS coords?

[monitor]

In looking at one of my images for a headstone from a cemetery, the left hand 'Info' pane has a GPS tab, other images do not show this tab.
1: what is the difference? - both are jpegs
2: can I add GPS info from within XnViewMP?
3: how?
TIA

[XnTriq]

Welcome to the forum, monitor.

1. Not all cameras come with built-in GPS, and the GPS tab in MP's info page only shows up for geo-tagged photos.
2. Select one or more JPEGs In the browser and go to Tools → Metadata → Edit GPS data.

[monitor]

Thank you, that works.