I found a sample script on Google Code about : Google Maps Javascript API V3 Overlays - http://code.google.com/apis/maps/documentation/javascript/overlays.html#OverlaysOverview

And I want to apply this code to other countries (France, spain...) but I don't know where/how to find the Geometry code like in this script (see commented line)

Here is the code:

var australia = new google.maps.LatLng(-25, 133);

    map = new google.maps.Map(document.getElementById('map_canvas'), {
      center: australia,
      zoom: 4,
      mapTypeId: google.maps.MapTypeId.ROADMAP
    });

    layer = new google.maps.FusionTablesLayer({
      query: {
        select: 'geometry', 
        from: '815230' // This one
      },
      styles: [{
        polygonOptions: {
          fillColor: "#00FF00",
          fillOpacity: 0.3
        }
      }, {
        where: "birds > 300",
        polygonOptions: {
          fillColor: "#0000FF"
        }
      }, {
        where: "population > 5",
        polygonOptions: {
          fillOpacity: 1.0
        }
      }]
    });
    layer.setMap(map);

P.S. I tried to change the google.maps.LatLng(-25, 133) to France Lat&Long but this is used only to center the map on that position.

Thank you for your help