Recoil Water Hose

Moreover, what is the general theory of relativity and Einstein's how does it take for the darkness of the black holes?

Newton: every action has an equal but opposite reaction.
Black holes: gravity is so powerful that it sucks everything, like a giant vacuum cleaner. It's everything, including light.

A hose back because every action has an equal and opposite reaction. The action in the pipe is for example the pressure in the water pipe pushing. This action has an opposite reaction is to push the pipe in the opposite direction of the water.

He steps back because of one of Newton's laws. At every action there is an equal and opposite reaction. The action of water being forced to leave the high pressure hose. The reaction is water pushing on the pipe with equal force. The same concept can be used to explain how a spacecraft is powered.

About black holes, I think it is due to the deformation of the 3D space itself due to gravity. This explains why the starlight is bent when it passes between the sun and the earth. Not too sure whether the answer you are looking for.