How to use it ?
- Simply download and run the installer (Windows) or install the package (note that GNU/Linux packages are also in .deb format, check for the deb tag in the file name).
- Then, to change the UI language, in OOo, go to the menu Tools>Options>Language Settings>Languages. Modify the language in the drop-down list, close OOo and the Quickstarter (in the system tray) if activated and start OOo again.
Go to the download page (link bottom right of this page), there is a link that leads directly to the language packs (see Get all platforms, languages, language packs). Search for your language, one row is for the full installer and the second row is for the language pack.
Note that it's easier to install the en-US (default) version and then install your language pack. Especially if you want to communicate in the forum without any translation differences.