I understand your pain. LOL, the funny thing is that Arabs will always tell you it's easy but they don't realize how complicated it is for a beginner! It took me some time to get a hang of Arabic plural forms. They can be very unpredictable. Basically, we have Female plural, Male plural, and Irregular plural. The simplest one is plural for feminine, as you almost always just change the end of the word to "-aat". But not all feminine words take that form though. There are many words that follow the same pattern when it comes to plurals. For instance: madinah (a city) is "mudun" in plural kitaab (a book) is "kutub" GHurfah (a room) is "GHuruf" Male and irregular plurals are really tricky. The best thing to do is just use them again and again until you memorize them clearly. Once you get a hang of it yourself, you will soon discover that there are more difficult grammar rules in Arabic that tends to complicate things with plurals - such as when we have case endings on the words (الإعراب). Good luck!