Android Question how to add a label in gmap

You cannot add a view to the map.

like Erel said, it is not possible to use buttons and so on in the InfoWindowAdapter, even if you load an layout in it. The only way is to listen for marker click events with OnMarkerClickListener and display your own complete view directly, which will be some work...
Alternativly you can use the OnInfoWindowClickListener to raise an event when the user clicks the google maps InfoWindow.

I have seen other apps which have a button and showing data in a label
app like hailo, how would I go about doing it as just clicking randomly on the map would not convey
to the user what was required ?

OK I found out how to add controls to maps using panels
exactly what I was looking for Thanks