Edit in JSFiddle

JavaScript
HTML
CSS
Result

var geocoder;
var map;
function initialize()
{
    geocoder = new google.maps.Geocoder();
    map = new google.maps.Map(document.getElementById("map"),
    {
        zoom: 8,
        center: new google.maps.LatLng(22.7964,79.5410),
        mapTypeId: google.maps.MapTypeId.ROADMAP
    });
}

function codeAddress()
{
    var address = document.getElementById("address").value;
    geocoder.geocode( { 'address': address}, function(results, status)
    {
        if (status == google.maps.GeocoderStatus.OK)
        {
            map.setCenter(results[0].geometry.location);
            var marker = new google.maps.Marker(
            {
                map: map,
                position: results[0].geometry.location
            });
        }
        else
        {
            alert("Geocode was not successful for the following reason: " + status);
        }
    });
}

<html>
<head>
<title>Google Maps API v3 Example : Geocoding Simple</title>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<script type="text/javascript">
</script>
</head>
<body onload="initialize()">
<div align="center" style="height: 30px; width: 530px">
<input id="address" type="textbox">
<input type="button" value="Geocode" onclick="codeAddress()">
</div>
<div id="map" style="height:200px; width: 530px"></div>
</body>
</html>