MMORPG for a begginner?

So I've been trying to do more gaming recently and after finishing up SAO (anime) I thought I'd try out a MMORPG. However I honestly have no idea where to start. First off I prefer something Free to download since I just want a taste of what MMOs are like. I also have a Mac so it would need to be playable on ISO. There where also a few things that interested me in particular with the different MMOs in SAO. Such as race, skills, and being able to connect to other people you probably would have never met irl. So if you know of a good game to try please recommend it and link it if you can. Thanks!