Translate your favorite sites into Arabic using a service such as Google Translate. If you have a particular site that you read on a regular basis, read the site first in English and then translate it into Arabic. The translations won't be perfect, but they can be a good way to pick up key phrases and words that are commonly used in everyday language.
Take an online course at a community college or university. More and more educational institutions are offering full courses in a variety of areas online. Students interact with teachers and even other students entirely using via their computers and resources like online textbooks and forums. Check educational institutions' websites to see if they offer online Arabic language courses.
Use online resources, such as Learn Arabic Online or Arab Academy. These sites are dedicated to teaching the Arabic language over the Internet. You can download resources that will help you learn common words, common phrases and even conversational Arabic at your own pace right from your computer at your own convenience.