Her er det som står av forklaring på woothems
Before we start
All our themes will support localization and include a language file (.po or .pot file) which contains all the English texts. You can find this language file inside the theme folder in themename/lang/.
Setup WordPress
The first step is to make sure your WordPress config file is setup with your locale. Open wp-config.php and modify the line below, or add it if it is missing. We’ve set it to Norwegian in the example below. See the complete list of language codes and country codes to find your exact locale.
1/**
2 * WordPress Localized Language, defaults to English.
3 *
4 * Change this to localize WordPress. A corresponding MO file for the chosen
5 * language must be installed to wp-content/languages. For example, install
6* de.mo to wp-content/languages and set WPLANG to 'de' to enable German
7 * language support.
8*/
9 define ('WPLANG', 'nb_NO');
Once this has been done you need to translate the language file in the theme using a plugin.
Translate using Codestyling Localization plugin
