The first thing that God did to deal with Adam and Eve's sin was to cover them with innocent blood:
Also for Adam and his wife, the Lord God made tunics of skin and clothed them. (Genesis 3:21)
God killed an animal of some sort--probably a sheep or ram or even a goat. He took its bloody skin and made garments for Adam and Eve to wear. With this act, God revealed to them that the cost of covering their sin was the shed blood of an innocent victim. Only blood can cover sin. Adam and Eve had tried to cover themselves with fig leaves, but that was inadequate because no blood was involved. They were still in their sin.
Keep in mind, that animal sacrifice was only a symbol of covered sin; the death of a lamb could never truly take away the sin of man. Only a sacrifice equal in stature to man would qualify. In other words, only the shed blood of a human being would be sufficient to cleanse human sin. Not just any human would do; it had to be a human without any sin of his own, a human who was already pure and spotless and holy. Jesus Christ, the sinless Son of God, born of the virgin Mary, is the only person who met the requirement. God sent His only begotten Son as a sacrifice to ransom us from sin because no