First, you need to find something to look at. When you first attempt to see an aura this way, only look at an object or at an animal. This method requires you to stare hard at someone or something, and if a person is to ask what you're doing it will break your concentration. I suggest you use an animal, because not everyone can see auras in objects, and some objects don't have auras.
Now, you need to concentrate on your subject. If you are using a person or animal, the best place to focus is the head. On an object, pick the most used part of the object (example: the point of a pencil). Stare at it until your vision starts to blur over, and look around the image. Do you see any color surrounding it? Or do you feel as if you can almost see it?
This can make your eyes hurt, so you may not want to practice too often for a while. But if you feel ready to keep it up, then go for it! Remember, not everyone can see aura with their eyes open, so don't be discouraged.