This is just a iframe example, I write it in hurry so if there any error please leave a comment i'll make it correct.
I hope this will help
<html>
<head>
<title>Untitled 1</title>
<pre lang="Javascript"><script language="JavaScript">
function go(loc){
document.getElementById['calendar'].src = loc;
}
</script>
</head>
<body>
<iframe id="calendar" src="about:blank" width="1000" height="450" frameborder="0" scrolling="no"></iframe>
<form method="post">
<input name="calendarSelection" type="button" önclick="go('page1.aspx')" value="Day" />
<input name="calendarSelection" type="button" önclick="go('page2.aspx')" value="Week" />
<input name="calendarSelection" type="button" önclick="go('page3.aspx')" value="Month" />
</form>
</body>
</html>
Thanks