First, create the structure of directories emulating the one from article 2. For example: make a copy of the existing directory with English files.

Rename the default directories htdocs/locales/en-US/ and plib/locales/en-US/ using your own language code instead of the default one (en-US). The first two letters stand for the language name (http://userpage.chemie.fu-berlin.de/diverse/doc/ISO_639.html) and the other two stand for the country name (http://userpage.chemie.fu-berlin.de/diverse/doc/ISO_3166.html), e.g. for Russian these directories should be renamed to htdocs/locales/ru-RU/ and plib/locales/ru-RU/. Further this four-letter name of the locale will be regarded as <locale_name>.

Now you have all directories and files ready for translation. You should start your translation with the interface files, as you will need items from them when translating help pages.

The plib/locales/<localeID>/ directory contains files with all interface and context help messages used in Plesk. All are contained in two files: conhelp_<localeID>.php and messages_<localeID>.php. These files contain entries of the type: 'key' => 'message'. The 'message' part should be translated. The ‘key’ part is used for fetching the message from the file.

The htdocs/locales/<localeID>/help/ directories and subdirectories contain HTML help files. These files can be translated using a text editor. Please note that they include php-code. In the process of translation this code should be left as it is and inserted into a proper (by context) place. In the cert.html, cert_upload.html and cl/cert_upload.html files, the if .. then .. else .. construction should be left as it is, the text inside of it should be translated.