Sit in a quiet room so that there is no noise around you. When there are less people or noise around you, you will focus on things through your eyes. That will help you visualize things around you later on when you exercise on other things.
The lights should remain dim. When the lights are dim, you will concentrate on things even more with your eyes. You will try to focus on things which are around you and it will help you focus on other things through your eyes.
This is very much necessary. Since you have been asked to sit in a quiet room and you should dim the lights, it is very much necessary that you are comfortable in the room you are sitting. If you are not comfortable, you will concentrate on things which are bothering you. Therefore, try to be comfortable, so that you can only work on your visualization and your eyes.
Once you are comfortable in a quiet room and once you know how to focus on things, now is the time for you to notice things around you. Look around and see what things and focus on them. Notice each and everything so that you can later remember what you have seen.
Once you are done with looking and focusing things around you, then it is time for you to close your eyes. Close your eyes and visualize each and everything that is around you. It will help you create images in your mind and you will understand how to remember things which have been around you when your eyes were open. Moreover, once your eyes are closed, it is the perfect time for you to work on your visualization.
When you are done with exercising while your eyes were closed, it is time for you to open your eyes and see things around you. It will be like a test for yourself as you will be able to check the things that you have identified with your eyes closed. You will know whether you have identified all the things correctly or not. If you have, it means your visualization has improved.