You can use javascript for this, here you have the code:
<html>
<head>
<title>Javascript Checkbox Visibility</title>
<script type="text/javascript">
function showHide()
{
if(document.getElementById('Checkbox1').checked)
{
document.getElementById('Text1').style.visibility = 'visible';
}
else
{
document.getElementById('Text1').style.visibility = 'hidden';
}
}
</script>
</head>
<body>
<p>
Check mark the checkbox to set the visiblity property of textbox.
It will allow you to show/hide the textbox control dynamically.
</p>
<p>
<input id="Checkbox1" type="checkbox" onclick="showHide();" checked="checked" /><label for="Checkbox1">Show/Hide</label><br /><br />
<input id="Text1" type="text" />
</p>
</body>
</html>