Some photos do not have GPS in their metadata. You can manually set their geo coordinates using a map. Select photos and right click on any of the selected photo, the context menu will popup, and click on "Set GPS Location".
The Geocoding map window will be displayed. You can pan the map by dragging with left mouse button down, and zoom using mouse wheel. Click on a location will populate the coordinates in the latitude and longitude input boxes.
Click "Set" button when ready.
If the selected photos do not have a place name, you can assign a place name manually. Select photos and right click on any of the selected photos, the context menu will popup, and click on "Set Place". A window will popup. Select an existing place from the list or create a new place and then confirm. The selected coordinates will be assigned to the selected photos and you will be able to see them from the Map view.