When you launch the program for the first time, it will prompt you to choose a language:
Once launched, you can change the language using the Look & Feel > Language menu.
The program’s menus, dialogs, and messages can be translated from U.S. English to other languages besides those listed above. The GreekToMe.pdf file (written in English) has detailed instructions on how to do this. The Downloads page has the Latest "Starter" Internationalization File.