I threw this together quickly, I thinks its about there, let me know...
<html>
<head>
<title>Create XML</title>
</head>
<body>
<?php
if (isset($_POST['Submit'])) {
// Collect post data from submitted form
$name = $_REQUEST['name'];
$val1 = $_REQUEST['val1'];
$val2 = $_REQUEST['val2'];
$val3 = $_REQUEST['val3'];
// Creates a new document according to 1.0 specs
$document = domxml_new_doc("1.0");
// Lets create an element and call it root, we will then append it to the new document.
$rootElement = $document->create_element($name);
$new_node = $document->append_child($rootElement);
// Lets create a new node called "Items" and append that to the root node.
$itemsElement = $document->create_element("movie");
$items_node = $new_node->append_child($itemsElement);
// Now go into a for loop in which we will create, set, and add five nodes to our Items node.
$item = $document->create_element("1st");
$item->set_content($val1);
$items_node->append_child($item);
$item = $document->create_element("2nd");
$item->set_content($val2);
$items_node->append_child($item);
$item = $document->create_element("3rd");
$item->set_content($val3);
$items_node->append_child($item);
// Lets dump this structure out to a file called output.xml
$document->dump_file("output.xml");
}
?>
<form action="" id="form" method="post">
Enter your name and top 3 movies
<label>Name:</label><input type="text" name="name" />
<label>1st Place</label><input type="text" name="val1" />
<label>2nd Place</label><input type="text" name="val2" />
<label>3rd Place</label><input type="text" name="val3" />
<input type="submit" name="Submit" value="Submit" />
</form>
</body>
</html>