Imagine you are standing at the side of a large lake, with your zen friend keeping you company. You look out on the lake and see a rowboat slowly moving across the water. At this point your friend says to you, "Stop the distant rowboat using just your mind."
At first you may laugh, or imagine some kind of telekinetic powers, and think your friend is joking. But then you look at him and see that he is quite serious. What in the world is he talking about? He will not explain any further, and the statement troubles you all day. That evening you go home and meditate, and during the meditation: Aha! You suddenly understand what he was saying.
I do not mean to dismiss the "Aha!" experience, but I will give away the "trick" of the koan right here. (Not that this does not leave some "Aha!"!) The lake, the rowboat, and the motion all exist in your mind. It does not take any telekinetic powers to stop the rowboat -- you only need to stop breaking the world up into pieces. The rowboat is not fundamentally different from the water in the lake, or, for that matter, from you or from the man rowing the boat. Once there is no rowboat, no water, and no motion in your mind you have indeed done as the koan asks.
Some people may be happy with that explanation of the koan, and that is fine. But that is really an intellectual "explanation" of the koan and does not stop the boat. The idea is to meditate on the koan until you personally experience the dissolving of subject and object. Even if it seems inconceivable, it really is possible.
The usual position for the eyes in Zen meditation is open. In some schools it is suggested to look slightly downward at the floor a few feet in front of you. At times it may be suggested to close the eyes. When I am meditating I sometimes like to look all around. After the differentiation of the world into separate objects has fallen away it can be fascinating to just look around. To look at the table and the chair but not to see them as separate from the carpet and the wall, etc. It can be fleeting, though. As soon as you think, "Hey, I'm really doing it!", it suddenly slips away. With practice, though, the slipping away occurs less and less.
So the next time you are meditating, or just sitting around, you might want to see if you can stop the distant rowboat using just your mind.