How to Use Add-ons for Firefox
Firefox add-ons come in three types: extensions, which alter Firefox's operation; appearance add-ons, which change the browser's theme; and plugins such as Flash Player and Silverlight. The Add-ons Manager lists the installed add-ons of each type and provides a method for enabling or disabling each, as well as sometimes offering additional options. You install and remove extensions and appearance add-ons through the Add-ons Manager itself, but you install plugins from the websites of the creators and remove them through the Windows Programs and Features Control Panel.
Click the menu button and choose "Add-ons" to open the Add-ons Manager. Check the "Get Add-ons" tab to see a list of recommended extensions and themes. Pick one to learn more about it and press "Add to Firefox" to install it, or search for one and click "Install." For more details on any add-on on the search page, click "More." The details page might also include a link to the developer's website for additional help. After you install an extension, click "Restart Now" if prompted.
Work With Add-Ons
Every add-on works differently. Some work silently, offering no options or menu items, while others have settings. If an extension has settings, it usually displays an "Options" button on the "Extensions" tab of the Add-ons Manager. Some developers place extension settings in a button that the extension adds to your toolbar. If you can't figure out how to use a particular extension, check the developer's website or search for the extension on Mozilla's add-ons website (link in Resources) to learn more about it. To stop using an extension, click "Disable" in the Add-ons Manager or click "Remove" to uninstall it permanently. Unlike extensions, appearance add-ons work only one at a time: Click "Enable" by the theme you want to use on the "Appearance" tab.