How to install languages in WordPress
In WordPress you can change the default language by installing a new one. This can be done either manually or automatically with the help of a plugin. For some languages there are installation packs for the whole WordPress applications that are configured by default to use the particular language.
In case you want to use more than one language per site you have to create a multilingual site. For more information on this read the tutorial on how to set up a multilingual site in WordPress.
Installing WordPress in a Different Language
The WordPress installation pack that you can download from the homepage of the official WordPress site is in U.S. English. However for many languages it's also offered in those particular languages. For example, you can download an installation package that's configured to work directly in French or German. For some of these languages there are subdomains on the official site (e.g. fr.wordpress.org, de.wordpress.org, etc.) and you can download the installation package in the particular language from there. For other languages installation packs in those languages are offered on other sites. You can check on this page of the official site to see if there's a link to such a site for the language you're looking for.
Installing Languages Automatically
Installing Languages Manually
To install a language manually:
- Download the language files of the particular language from the WordPress Language File Repository.
After you open the repository you'll see a list of directories corresponding to the different languages. The ISO codes of the language and the country are used for naming (e.g. fr_FR for French). Browse through the directory of the particular language and find the folder containing the language files (e.g. /fr_FR/branches/version-number/messages for French; you have to replace version-number with the actual WordPress version number). The language files are with .po and .mo file extensions. Download only the .mo files. The main file is labeled with the two ISO codes (e.g. fr_FR.mo for French).
- Upload the language files from your local computer to /wp-content/languages in the root WordPress folder on your hosting account.
If you don't have a languages folder inside the wp-content directory, create it and upload the files there.
- Modify the line define ('WPLANG', ''); that's in the wp-config.php file of your WordPress.
In the quotation marks put the ISO codes of the main language file. For example, if the file is fr_FR.mo then modify the line so that it looks like this: define ('WPLANG', 'fr_FR');
For some more details you can also check out the tutorial on how to install languages in WordPress.