Translation of User Interface strings in DrupaAdministration
How do I import languages to translate the base of drupal?
Go to http://drupal.org/project/translations and download them.
Untar (unzip) your language translations.
Then head on over to your Administer » Site Configuration » Localization page and click import (/en/admin/settings/locale/language/import)
You do not even have to enable the language first:
Choose the language you want to add strings into. If you choose a language which is not yet set up, then it will be added.
Near as I can tell, ignore the installer.po file and simply choose to upload the file with the language name in it.
Be very careful to change the "Import into" select field. It's way too easy to forget to do this, and it will overwrite your 100% translated Chinese and turn it into 2/3 translated Thai. Not that this happened to me or anything.
Manual upload of translation files for now, but there must be a better way.
Also see questions above especially regarding the translated strings in .po files in almost every contributed module Drupal has. Agaric doesn't want to have to upload those by hand also. (Are they supposed to be dumped in a folder together and there are tools to merge them into one?)
You can see in the attached image file that this translates the admin pages pretty well, but those pesky user-set site strings are not translated and contributed module strings are not (yet) translated.
Answer to number one and maybe some help with number two:
Searching for information on .po files in Drupal contributed modules, I found the post Please clarify: Manual import of module po files needed?
Ahh, happiness and light, it pointed me to the autolocale module: http://drupal.org/project/autolocale
(This functionality will be core in Drupal 6.)
Automatic translation of user interface strings sure is a beautiful thing.
NOTE: I uncheck the box to replace all existing translations-- because I've downloaded these translations from Drupal.org, I know not all of them are in the .po files of Drupal core.
Also, received a bunch of plural string cannot be parsed errors on the Dutch.