Question

I have a form and I want if user submit that form then the action page will open in pop up

Answer 1

<script type="text/javascript">
function openwindow (url) {
   var win = window.open(url, "window1", "width=600,height=400,status=yes,scrollbars=yes,resizable=yes");
   win.focus();
}
</script>

<button value="send" onclick="openwindow('http://google.com')" />

or you use the target-attribute, like the other said. the target-solution is the better choice if you want to pass data of form-elements to your action page

keep in mind that popup-blockers may block this action