Thanks all,
Madiw , you will find the files and instructions on how to use arabic language with classipress in this thread :
Thread: [READY 2 USE] Arabic translation and RTL CSS .
the translation files on that thread are for ClassiPress version: 3.0.5.3 , that is the version I am using right now on my site. maybe they do work fine with the newest version of classipress, but i did not test it so i can't say.
bye for now.