By focusing into something.
Take a moment, and look at the tip of your fingers. Do you feel it? You feel a pressure or sensation at the top of your finger, where you look at it. It is because as you focused at your finger, energy flew into it. Same goes if you concentrating, focusing at one point on your body with closed eyes. YOu visualize an ergy moving in your body, and that energy will actually move. The point of view might be a big question when it comes to closed eye visualization.
I usuall visualize with my eyes POV or a close up POV. For exemple if I visualize my 6th chakra I cant do it with my eyes POV, so the thing that I do is that I view it from right behind my 6th chakra right in front of the back intestion of my 6th chakra.
You can't realy explain how the POV works when it comes to visualizing, you have to experienc it.
You also have to practice it, it might seems horryble at the beginning but practice makes perfect.