AddToAny's official Joomla extension is available as a plugin for Joomla 3.0+ and Joomla 2.5.

To install in Joomla 3.2+:

• Go to Extensions > Extensions Manager > Install
• Under Install from Web, search for AddToAny
• Enable AddToAny from the Plugin Manager, then you can click the plugin's name to configure AddToAny

To install in Joomla manually (versions 3.1.x - 2.5):

• Download AddToAny for Joomla
• Go to Extensions > Extension Manager > Install
• Under Upload Package File, choose the ZIP file you downloaded, then click Upload & Install
• Enable AddToAny from the Plugin Manager, then you can click the plugin's name to configure AddToAny

An older unofficial extension for Joomla 1.5 is available here. Alternatively, you may consider the standard sharing button code.