This tutorial will show you how to install now language pack to your Joomla website.
First of all you should visit the official Joomla website at http://joomla.org and download the language pack you need. You can download the language packs here
Make sure you are downloading the language pack that meets your Joomla engine version.
When the download is complete open Joomla admin panel and go to Extensions > Install/ Uninstall (Extensions>Extensions Manager for Joomla 1.6)
In the Upload Package File field click the Browse button and select the download language pack .zip file. Click Upload & install button.
Set Default Language
To set different default website language in the Joomla admin panel go to Extensions > Languages Manager, check the language you want to set as default and click the Default button at the top.
Refresh your website and you’ll see your Joomla in new language.