First, you teach the child to recognize the letters of the alphabet. That is generally a fairly easy task. Second, you teach the child the sounds the letters stand for. Various phonics programs do that in a variety of ways. However, what is most important in this phase is that the child be permitted to develop an automatic association between letters and sounds, for that is crucial in becoming a good phonetic reader.
Phonic drills help a child achieve that needed automaticity.
Third, you give the child interesting little stories to read so that he or she can practice sounding out new words. That's all there is to it. It is easy. Child learns the alphabet first. Child learns the sounds the letters stand for by drill so that he or she develops an automatic association of letters with sounds.