Put this into the <head> of your html:
[tt]
</script>
function popupPage(url,w,h) {
var windowprops = "location=no,scrollbars=no,menubar=no,toolbar=no,resizable=no" + ",
left=100,top=100" + ",width=" + w + ",height=" + h + ";";
// change the top and left values to adjust window position
a = window.open(url,"popup",windowprops);
a.document.open();
a.document.write("<html><body><h3>Message Header</h3><p>Message text goes here.</p></body>"

;
//here is the message that will be displayed
a.document.close();
}
</script>
[/tt]
If you want to open a popup when you click the link, do this:
[tt]
<a href="#" onclick="popupPage('',200,300); return false;">open new win</a>
[/tt]
If you want it to appear when you click a button, do this:
[tt]
<input type="button" value="open new win" onclick="popupPage('',200,300)">
[/tt]
If you want it to load autamatically when page finish loading, do this:
[tt]
<body onload="popupPage('',200,300)">
[/tt]
You can adjust the window winth/height by changing the values in function call:
popupPage('',
W,
H)
And, finally, it's a good idea to search HTML and JS forums/FAQs first, because there questions are discussed very ofter.