If you're looking to add a favourite icon beside the domain name in your browsers address bar, then this works for Microsoft Internet Explorer 7 and Firefox:
Simply add it between the HEADER tags in your web pages (between the < and > characters)
link rel="Shortcut Icon" href="images/favicon.ico"
Note:
For some reason the ico file must go into the 'images' folder for it to work; anywhere else and IE doesn't show it.
