My sidebar with upcoming events does not show

You want to embed in your web page a stand-alone sidebar with upcoming events, as shown on the LuxCal Demo page.
You've nicely added the following two lines to the head section of your index.html page:

<link rel="stylesheet" type="text/css" href="mycalendarfolder/css/css_sbar.php">
<script type="text/javascript" src="mycalendarfolder/common/toolbox.js"></script>

and within the body you've added the following PHP-code:

<?php
$sbHeader = 'My Upcoming Events';
include './mycalendarfolder/lcsbar.php';
?>

all exactly as described in the LuxCal installation_guide.html.
However, the sidebar does not show :o

Because . . . you have forgotten to rename your index.html page to index.php