Below is a description of breathing meditation gracefully provided by Tashi Nyima of the Great Middle Way.
Choose a conducive environment. Find a nice, quiet place where you won’t be disturbed for fifteen minutes or longer. Sit down, relax, and rest your hands on your lap. You can sit on the floor cross-legged with the support of a meditation cushion, or on any chair with your feet resting on the ground. It is not necessary to force yourself into a lotus position if you are not used to it.
Regardless of how you sit, it is important to maintain the natural curve of your back. That means no slouching. People with chronic back problems who cannot sit for a prolonged period of time can explore other meditation positions.
Breathe slowly and deeply. Close your eyes softly. Direct your soft, unfocused gaze downwards. Begin by taking a few slow and deep breaths — inhaling with your nose and exhaling from your mouth. Don’t force your breathing; let it come naturally. The first few intakes of air are likely to be shallow, but as you allow more air to fill your lungs each time, your breaths will gradually become deeper and fuller. Take as long as you need to breathe slowly and deeply.
Be aware. When you are breathing deeply, you will begin to feel calmer and more relaxed. That is a good sign. Now, focus your attention on your breathing. Be aware of each breath that you take in through your nose. Be mindful of each breath that you exhale with your mouth. Continue focusing on your breaths for as long as you like.
If you find your attention straying away from your breaths, just gently bring it back. It may happen many times. Don’t be disheartened. What’s important is to realize that you have wandered and bring your attention back to where it should be. As you develop greater focus power, you will find it easier to concentrate. Ending the session. When you are ready to end the session, open your eyes, and stand up slowly.