The code below is from https://developers.google.com/maps/docum…
which is meant to be used for adding a custom overlay image in Google Maps with Google API v3. I've been looking at it for awhile and can't figure out what I need to change in order to get a full country image rather than one small little building. I'd also like to switch the image. Any help you can offer would be much appreciated.

<!DOCTYPE html>
<html>
<head>
<title>Overlaying an image map type</title>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no">
<meta charset="utf-8">
<style>
html, body, #map-canvas {
margin: 0;
padding: 0;
height: 100%;
}
</style>
<script src="https://maps.googleapis.com/maps/ap…
<script>
var map;
function initialize() {
var mapOptions = {
zoom: 18,
center: new google.maps.LatLng(37.78313383212, -122.4039494991302),
mapTypeId: google.maps.MapTypeId.ROADMAP
};
map = new google.maps.Map(document.getElementById(…
mapOptions);

var bounds = {
17: [[20969, 20970], [50657, 50658]],
18: [[41939, 41940], [101315, 101317]],
19: [[83878, 83881], [202631, 202634]],
20: [[167757, 167763], [405263, 405269]]
};

var imageMapType = new google.maps.ImageMapType({
getTileUrl: function(coord, zoom) {
if (zoom < 17 || zoom > 20 ||
bounds[zoom][0][0] > coord.x || coord.x > bounds[zoom][0][1] ||
bounds[zoom][1][0] > coord.y || coord.y > bounds[zoom][1][1]) {
return null;
}

return ['http://www.gstatic.com/io2010maps/tiles/…
zoom, '_', coord.x, '_', coord.y, '.png'].join('');
},
tileSize: new google.maps.Size(256, 256)
});

map.overlayMapTypes.push(imageMapType);

}

google.maps.event.addDomListener(windo… 'load', initialize);

</script>
</head>
<body>
<div id="map-canvas"></div>
</body>
</html>