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1. download the archive
2. unzip and drop all the files, as is, in your plugins/sabre directory.
3. Enable the plugin in the WP Admin >> Plugins section.
4. Change the parameters in the WP Admin >> Manage >> Sabre tab.
5. Other languages Sabre is delivered in English and French but can be easily used with other languages. You just have to create a file sabre-xx_YY.po (xx_YY being the language code of your WordPress settings. Eg: fr_FR for French) from the existing file sabre.pot using PoEdit. Then, just translate the text strings located after the "msgid" tag and put the translated string after the "msgstr" tag. The resulting sabre-xx_YY.mo file has to be stored in the sabre/languages directory. Alternatively, you can find the translation files (.mo et .po) of some languages in the FAQ page.

If you are upgrading from a previous install, don't forget to deactivate Sabre before overwriting the older files with the new ones. Then activate it again so Sabre can apply the required database and options updates.