Favicons are those little images that show up on the tab for the browser page. They are also stored with bookmarks if someone bookmarks your page.

Where the template gets the favicon for your website varies with templates, but in most cases there in a favicon.ico file right at the root of your template folder. You can simply remove that one and upload your own using a ftp file manager or through the file management at your hosting company.

The favicon.ico graphic must be the correct file type. You cannot simply rename a .jpg or .png for use as the favicon.

There are many sites on the internet that will transform a .jpg, .gif or .png file to the proper format. You can upload your own graphic file, or create one at the site. The end result is a file that is only 16px by 16px, so it is best to keep it very simple.

One of the free sites is www.favicon.cc

Other things that you might consider is adding icons for Apple devices. The icon for the iPad tablet is larger than a favicon. If you do not specify this file, if some one wishes to place a shortcut to your site on their tablet, Apple will take a screenshot of your site and use that as the graphic. This may not be desirable. See the below link for instructions on how to add Apple icons to your site.