To add a new language please go to:

Admin -> Localization -> Languages -> create new language

Note: Please make sure you have language code correct (e.g. fr, es …) : Click here

create a language - EasyAds

Then files will be created in:

APPLICATION_ROOT/engine/messages/LANGUAGE

create a translation - EasyAds
The main file is app.php, you can go ahead and translate in that file.

change a translation - EasyAds

When translation file is ready, From:

Admin -> General -> Change Site Language.

And the results can be seen here for example:

Translation result - EasyAds