The source code repository location is hosted at GitHub. You can access the entire code repository at http://github.com/openlayers/ol3.
Feel free to download a copy and play around with it yourself. When you become an advanced user, you can submit evolutions to the official source code base and become a contributor to the library. Without going so far, it cannot hurt to download a copy of the code base and look around it yourself to figure out how it's really working!