Hi Zeid Fanous,
If you have access to a Moodle server in arabic, you can use the procedure described in the Language Customization Moodle documentation to find the component and string identifier. Once you make the local change and you have verified that it worked perfectly, go to AMOS and translate that component and string identifier you researched. Send your contribution to the language pack maintainers.
I personally prefer to make a local customization in a local sever and only upload the ZIP file (with all the *.php files that were inside the moodledata/lang/xx_local/ folder) containing all the local translations into AMOS once I have finished translating all of one module/plugin.
Feel free to ask for more help if you are stuck or you can not follow the instructions in the documentation pages.