I have researched around quite a bit, but can't appear to locate where I ought to be saving the code for that widget I have produced. It's a little baffling.

So, can anybody let me know where I ought to save my widget?

Thanks, John.

You have to place your widget code either in the functions.php file of the current theme, or inside a wordpress plugin. To be able to place it inside a wordpress plugin, produce a new folder within the plug ins folder and make up a .php file using the title from the folder you produced within that folder. For the reason that file, make use of this code to begin your wordpress plugin:

<?php
/*
Plugin Name: Name Of The Plugin
Plugin URI: http://URI_Of_Page_Describing_Plugin_and_Updates
Description: A brief description of the Plugin.
Version: The Plugin's Version Number, e.g.: 1.0
Author: Name Of The Plugin Author
Author URI: http://URI_Of_The_Plugin_Author
License: A "Slug" license name e.g. GPL2
*/
?>

Clearly, alter the values to something helpful for the wordpress plugin. After that you can paste your widget code into this file and it ought to be available.

Sources:

http://codex.wordpress.org/Writing_a_Plugin

http://codex.wordpress.org/Plugin_API

So far as I understand, widget (ie plug ins) use your wordpress-content/plug ins folder eg. wordpress-content/plug ins/YOUR WIDGET/

Is the fact that the thing you need?