Blender as comp tool

I’m thinking of learning Blender for compositing mainly and need some advice.
Where should I start learning? I’ve checked the docs, but they seem pretty short. Am I missing somthing? I know composting in nuke. So I don’t want to learn compositing. I rather want to find the right buttons in blender.

Can you recommend some resources? Also I’m interested in Python-Coding related to this. Would it be “easy”/doable to load opencv stuff to blender compositing? Maybe someone done it? And what about deep exr is there something like this in Blender?

I have too many questions :smiley:
But any hint on where to start is much appreciated (written form is good as well)

Thanks for your time