How to learn skeletal mesh animation?

I am a new to ue4’s engine feature skeletal mesh animation.When I open the official documentation about the section of this,what a surprise,I have no idea how to learn it.
I think mybe I lack of many knowledge about it, I hope someone can tell me a way to understand what dose the documentation say.Thanks.

Check out the Unreal Engine YouTube page there’s a lot of great videos on how to use their engine including videos on animation.