Piwik is a platform which you can extend and customise to your needs with Plugins. To get started installing a plugin, login as a Super User. In the top right menu, click “Settings”. In the “Platform” left menu click “Marketplace”. There are a few ways to install a plugin in Piwik:
Upload a Plugin ZIP file to Piwik: if you were given the ZIP file of a plugin, you will need to upload it to Piwik. To do so, on the Marketplace page click on “upload a zip file”.
Install a new plugin using the Marketplace: on the Marketplace page you can browse existing plugins, if you want to install one of those plugins, click on “Install” button.
Install a new plugin manually: this last technique only works if you have direct access to the Piwik server. Uncompress the Plugin zip file that you wish to install in Piwik. This should create a directory with the name of the plugin. Copy this uncompressed folder into your server in the directory path/to/piwik/plugins/.
By default, when you install a plugin it is not activated. To activate a plugin, go to the “Plugins” page in the Admin settings and click “activate” next to the plugin name.