To add a rotating image to a website built with Joomla 3, the following is one method that works and seems to be repeatable.
First, create your images to a standard size (height and width). Store these in a directory such as images/header/ and call them header#.jpg where # is the number of the image (eg:header4.jpg).
In the Joomla template file, find the <header> tag and add after this the following:
<img style="float-middle"; src="/<?php echo $this->baseurl...