First copy your style sheet "styles/ecommerce_white.css" as "styles/web4girls.css"
Then create a template folder "templates/web4girls".
The reason for doing this is to give you a copy of your styles file to work on and if you customise any html template files put them in "templates/web4girls" so you dont have to alter the originals. Also if the system is upgraded your customised styles and templates are not overwritten.
Go to Admin "CMS > Layouts". Add New.
Create a layout called "web4girls.
Layout Name, Customer Layour Name and Style Name all set to "web4girls"
Select web4girls for the templates and "Update". Now select it from the layouts list to make it active.
You can now edit "styles/web4girls.css" putting in Tahoma font where you want it. If you are using Windows others have suggested using Stylizer
http://www.skybound.ca/stylizer/ to edit your style file.
To make text right justified select all the text in any of the text input boxes and click on the right justify icon (8th from right). You can also set it in the css file using "text-align:right;"
Languages are stored in "messages/ar/messages.php" for Arabic. The other files contain other messages for other parts of the system.
HTH