Zim - A Desktop Wiki
The easiest way to contribute translations is to go to the launchpage website. Here you can colaborate with others to translate zim into your native language.
If you rather use offline tools like poedit you can either download the latest translation template or partial translation from launchpad or checkout the source repository for zim (see Contribute). To submit your updates upload the resulting .po file to the launchpad website again.
Zim using the GNU gettext tool chain for translations. The source package contains a "zim.pot" file which is the template. The directory "po/" contains translations, which are named "po/language.po" or "po/language_COUNTRY.po" where "language" and "COUNTRY" are the respective language and country codes for the locale.
To compile a new translation run:
$ ./setup.py build_trans
This will compile .mo files for all translations and put them in the directory "locale".
Now run zim from the source directory using:
$ LANGUAGE=language_COUNTRY ./zim.py
$ LANG=language_COUNTRY ./zim.py