Can you explain exactly how I should learn to Breathe correctly?

First, find a comfortable position in which you can relax and focus your attention on your breathing, fully experiencing the flowing of air in through the nose and out through the mouth . . . in and out . . . allowing your body to breathe according to its own natural rhythm, easily, without effort. Notice yourself relaxing more and more as you focus on the flow of air coming into your body and going out again.If you find yourself being aware of your body because you are distracted by some ache or sensation, focus again on your breathing. In and out. . In and out. . Relaxing more and more.