I am unable to type in Arabic in Word, how do i install a "language pack"?, I am unable to type in Arabic in Word, how do i install a "language pack"?

I need to be able to type in Arabic on my macbook. I figured out how to change my typing language into Arabic but as soon as I type a word into a word document, I hit the space bar and it moves all the letters around. I was told by the help desk at my university it is because I do not have a "language pack" installed - whatever that means.

Help!

passiondropp.