how to insert google map

<script>
var lat = 0; lon = 0;
var x = document.getElementById("demo");
function getLocation() {
    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(showPosition);
    } else {
        x.innerHTML = "Geolocation is not supported by this browser.";
    }
}
function showPosition(position) {
    lat = position.coords.latitude;
    lon = position.coords.longitude; 
}
</script>

function initialize() {
  var mapProp = {
    center:new google.maps.LatLng(lat, lon),
    zoom:5,
    mapTypeId:google.maps.MapTypeId.ROADMAP
  };
  var map=new google.maps.Map(document.getElementById("googleMap"),mapProp);
}
google.maps.event.addDomListener(window, 'load', initialize);