Я думаю, что вы хотите найти здесь:
https://developers.google.com/maps/documentation/javascript/examples/infowindow-simple
// This example displays a marker at the center of Australia.
// When the user clicks the marker, an info window opens.
function initialize() {
var myLatlng = new google.maps.LatLng(-25.363882,131.044922);
var mapOptions = {
zoom: 4,
center: myLatlng
};
var map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
var contentString = '<div id="content">'+
'<div id="siteNotice">'+
'</div>'+
'<h1 id="firstHeading" class="firstHeading">Uluru</h1>'+
'<div id="bodyContent">'+
'<p><b>Uluru</b>, also referred to as <b>Ayers Rock</b>, is a large ' +
'sandstone rock formation in the southern part of the '+
'Northern Territory, central Australia. It lies 335 km (208 mi) '+
'south west of the nearest large town, Alice Springs; 450 km '+
'(280 mi) by road. Kata Tjuta and Uluru are the two major '+
'features of the Uluru - Kata Tjuta National Park. Uluru is '+
'sacred to the Pitjantjatjara and Yankunytjatjara, the '+
'Aboriginal people of the area. It has many springs, waterholes, '+
'rock caves and ancient paintings. Uluru is listed as a World '+
'Heritage Site.</p>'+
'<p>Attribution: Uluru, <a href="https://en.wikipedia.org/w/index.php?title=Uluru&oldid=297882194">'+
'https://en.wikipedia.org/w/index.php?title=Uluru</a> '+
'(last visited June 22, 2009).</p>'+
'</div>'+
'</div>';
var infowindow = new google.maps.InfoWindow({
content: contentString
});
var marker = new google.maps.Marker({
position: myLatlng,
map: map,
title: 'Uluru (Ayers Rock)'
});
google.maps.event.addListener(marker, 'click', function() {
infowindow.open(map,marker);
});
}
google.maps.event.addDomListener(window, 'load', initialize);