<form action="someform.php" method="post">
    Name: <input type="text" name="Name" value="Jim" /><br />
    Password: <input type="password" name="Password" /><br />
    Age: <input type="text" name="Age" /><br />
    <input type="submit" />
    </form>

<input type="hidden" name="Name" value="<?php print $_POST['Name']; ?>" />
<input type="hidden" name="Password" value="<?php print $_POST['Password'];
?>" />