This is take from http://www.zakairan.com/ZaKaiRansArticlesBooks/PranicBreathing.htm.
There are also many other webites, such as yoga websites, that also give the technique of pranic breathing.
Initially stand, preferably on the ground with bare feet, then later you may do this siting comfortably. Regardless, you should be as close to the ground as possible so that your prana tube is in the ground. (I prefer the laying down method, but use which ever you are most comfortable with) If you are sitting, your prana tube is even lower into the ground because it does not bend with your body, it stays straight.
Visualize and feel your prana tube that extends right through the center of your body, through the center of your brain, through your pineal gland, through your perineum, (just above your anus). It extends one hand length above your head and one hand length below your feet. Put your hand above your head briefly to see how far the prana tube extends. Look down to see how far this prana tube extends below your feet. (To visualize the width of your prana tube: place your index finger and thumb together to form a circle, this is the size of your prana tube).
Begin by breathing prana up from the earth through your prana tube to your heart chakra center. (You may draw in this prana coinciding it with the inhale of your physical breath. But be aware that prana is a constant in-flow, it does not go in and out). Feel this earth prana, the life force of Mother Gaia flowing through you and expanding your heart.
Now breathe in prana from the cosmic above your head, from the crown center. (You may once again breathe in prana coincidally with your physical breath). Draw this cosmic prana in through your pineal gland and feel it activate. Draw in this prana to your heart center. Feel the multidimensional, intergalactic, universal nature of this energy. Feel this cosmic life force energy expand you in a profound way, remembering your spiritual essence.
Now do them both at the same time. Draw in prana from below and above at the same time, up through your perineum to your heart and down through your pineal to your heart. Feel your heart expanding. Feel the complete balance that is created. Feel yourself centered in your crown, connected to the realm of Spirit, connected to the earth and balanced within your heart.