When you start working with After Effects, it will probably be overwhelming. There are tons of video tutorials online, but most of them focus on a particular effect and don't offer structured training that help beginners to get started.
If you are new to After Effects and don't know where to start, I recommend the following free training series
They start with the very basic stuff and give you the foundation to follow all the other tutorials that you find online. If you prefer books to video training, I recommend the book After Effects Apprentice by Trish and Chris Meyer.
To get started, it does not matter, which version of After Effects you own. If the training video is for CS5 and you already own CS6, its not a big deal. In the basics, all the versions are very similar.