How : click a button and display an existing page?

[onlo]

I can create a button and popup a window dynamically :

<form action="description.php">
<input type="button" value="How it works" onclick="openWin()" id='description'>
</form>
<script>
function openWin() {
myWindow=window.open('','','width=1000,height=500');
myWindow.document.write("<p>This is 'myWindow'</p>");
myWindow.focus();}
</script>

However, I want to click a button and display an existing page (a page already created with another tool), how can I do that ?

[Snaek]

I can create a button and popup a window dynamically :

What do you mean by dynamically?