Some items worth noting before you begin:
- In this article, we have chosen to add a language in SharePoint 2013 using the SharePoint 2013 language pack. Please note that if you are using SharePoint 2010, all steps are exactly the same.
- Bamboo Community Central has 3 templates: Community Central Home, Blog Home, and Forum Home template. In this post, we will be adding the language to a site that utilizes the Community Central Home template.
http://community.bamboosolutions.com/blogs/sharepoint-2013/archive/2013/11/08/add-a-new-language-pack-to-community-central-in-sharepoint-2013-and-2010.aspx