Some teachers refer to this practice as "open presence" because it involves being just lightly aware of whatever you're experiencing--internally or externally---right here and now. You're merely present.
The instructions are simple. Just straighten your spine while keeping the rest of your body relaxed. Take a couple deep breaths.
Keep your eyes open---though not so intently that your eyes begin to burn or water. You can blink. But just notice yourself blinking. Each blink is an experience of presence.
Now, let yourself be aware of everything you're experiencing--sights, sounds, physical sensations, thoughts, and emotions. Allow yourself to be open to all these experiences. Inevitably, as you begin this exercise, all sorts of thoughts, feeling, and sensations will pass through your experience. This is to be expected. This little exercise is in many ways like starting a weight-training program at the gym. At first you can lift only a few pounds for a few repetitions before your muscles get tired. But if you keep at it, gradually you'll find that you can lift heavier weights and perform more repetitions.
Similarly, learning to rest in simple, open presence is a gradual process. At first you might be able to remain open for only a few seconds at a time before thoughts, emotions, and sensations bubble up to the surface and consume your attention. The basic instruction is merely to be aware of everything that passes through your awareness as it is. Whatever you experience, you don't have to suppress it. Even latching on to irritations--"Oh, I wish that person next door would turn down his music" or "I wish the family upstairs would stop yelling at each other"--is part of open presence. Just observe these thoughts and feelings as they come and go--and how quickly they come and go, to be replaced by others. If you keep doing this, you'll get a taste of emptiness--a vast, open space in which possibilities emerge and combine, dance together for a while, and vanish with astonishing rapidity. You'll glimpse one aspect of your basic nature, which is the freedom to experience anything and everything.
Don't criticize or condemn yourself if you find yourself chasing after physical sensations, thoughts or emotions. No one becomes a buddha overnight. Recognize, instead, that for a few seconds you were able to directly experience something new, something now. You've passed through theory and ventured into the realm of experience. As you begin to let your experiences come and go, we begin to see them as less solid. They may be real, but you being to question whether they're true.
Experience follows intention. Wherever we are, whatever we do, all we need to do is recognize our thoughts, feelings and perceptions as something natural. Neither rejecting nor accepting, we simply acknowledge the experience and let it pass. If we keep this up, we'll eventually find ourselves becoming able to manage situations we once found painful, scary or sad. We'll discover a sense of confidence that isn't rooted in arrogance or pride. We'll realize that we're always sheltered, always safe, and always home.