<html>
<head>
<script type="text/javascript">
function enabl_element()
{
document.getElementById("hid").style.display="block";
}
</script>
</head>

<body>
<form>

<input type="button" id="enable" value="Enable" onClick="enabl_element()" />
<div id="hid" style="display:none">Show me</div>
</form>
</body>
</html>