Click the orange face icon at the very top of the home screen, next to the yellow pencil. You will find it there.
I just got my 2ds and I play mario kart 7 and pokemon y and much more to come. But please feel free to share your friend code and what games you play hopefully we can play against each other in the long run. I will start by posting mine 2380-4108-6229. My name is vel. And thanks and I will be looking forward to play online.
I might be planning to get a 2DS, however I'm curious as to whether it lets you play games on it from another generation of console, eg DSi, as I have quite a few for that.