Tutorial on 2d Dynamic Lighting and Shadows

While I know there are a few different assets in the store you can buy to do this, I'd like to attempt to do it on my own. The problem with that is, I'm not even sure where to begin. This is my first jump into game programming and unity so some of the concepts are a bit new to me. From what I've been reading, ray casters are the simplest solution. What I'd like to achieve is something like this https://www.assetstore.unity3d.com/en/#!/content/25933. I haven't been able to find a tutorial that seems to cover this fully. Any help is appreciated.

Thanks!