Welcome Harold.
What you are attempting is to create a 'trak' or sometimes called 'trac' of geocoordinates on a map. App Inventor has components, among them the LocationSensor, and Map that will you allow you to do it.
Use a Map LineString to display a track or elicit run time Markers with some additional effort (see the link). Exactly what you need to do depends on how you save the GPS points.
See App Inventor GPS Trak Basics . GPS Traks using Static Maps or Map Component shows how to do it using the Map component LineString (the preferred way in my opinion., The link also shows how to use a Static Map using a Google Map (more difficult for no real gain in advantage).
There are numerous discussions showing how to use the Map components to display a trak. I see if I can find you some links tomorrow.
Here is one LineString to draw a track