How do I call a PHP function? [closed]

Answer 1

In the form tag of your HTML page:

<form type="post" action="test.php">

File test.php

<?php
    function login_bar() {
    }

    // If you want to call the function on some button click:

    if (isset($_POST['submit']))
    {
        login_bar();
    }
?>

Answer 2

An HTML page won't process a PHP call. Change your page to page.php and then call login_bar();.