For Joomla 1.5.x version use plg_gtranslate.zip

For Joomla 1.6.x & 1.7.x versions use plg_gtranslate-1.7.zip

For other websites including Joomla 1.0.x, WordPress, Drupal and Magento you need to follow directions in general/readme.txt file.

After installing it on Joomla: 

- Modify robots.txt and add this line on the end of the file (replace yourdomain.com with your domain name). You can have more than one sitemap.

Sitemap: http://monmegastore.com/sitemap.txt

- Create sitemap.txt in the root folder with the following contents. You can remove the languages you don't want to be indexed to save translation traffic. (you can provide here more deep sitemap; one link per line. If you already have sitemap.txt you can append it.)

http://monmegastore.com/en/
http://monmegastore.com/af/
http://monmegastore.com/sq/
http://monmegastore.com/ar/
http://monmegastore.com/hy/
http://monmegastore.com/az/
http://monmegastore.com/eu/
http://monmegastore.com/be/
http://monmegastore.com/bg/
http://monmegastore.com/ca/
http://monmegastore.com/zh-CN/
http://monmegastore.com/zh-TW/
http://monmegastore.com/hr/
http://monmegastore.com/cs/
http://monmegastore.com/da/
http://monmegastore.com/nl/
http://monmegastore.com/et/
http://monmegastore.com/tl/
http://monmegastore.com/fi/
http://monmegastore.com/fr/
http://monmegastore.com/gl/
http://monmegastore.com/ka/
http://monmegastore.com/de/
http://monmegastore.com/el/
http://monmegastore.com/ht/
http://monmegastore.com/iw/
http://monmegastore.com/hi/
http://monmegastore.com/hu/
http://monmegastore.com/is/
http://monmegastore.com/id/
http://monmegastore.com/ga/
http://monmegastore.com/it/
http://monmegastore.com/ja/
http://monmegastore.com/ko/
http://monmegastore.com/lv/
http://monmegastore.com/lt/
http://monmegastore.com/mk/
http://monmegastore.com/ms/
http://monmegastore.com/mt/
http://monmegastore.com/no/
http://monmegastore.com/fa/
http://monmegastore.com/pl/
http://monmegastore.com/pt/
http://monmegastore.com/ro/
http://monmegastore.com/ru/
http://monmegastore.com/sr/
http://monmegastore.com/sk/
http://monmegastore.com/sl/
http://monmegastore.com/es/
http://monmegastore.com/sw/
http://monmegastore.com/sv/
http://monmegastore.com/th/
http://monmegastore.com/tr/
http://monmegastore.com/uk/
http://monmegastore.com/ur/
http://monmegastore.com/vi/
http://monmegastore.com/cy/
http://monmegastore.com/yi/

This will enable search engine indexing of the translated pages.