The LORD God commanded the man, saying, "From any tree of the garden you may eat freely; but from the tree of the knowledge of good and evil you shall not eat, for in the day that you eat from it you will surely die."
Adam and Eve were at the peak of promise and perfection when one conversation changed them and the entire human race forever. There did not appear to be any confusion when God gave the instructions, but the serpent brought confusion with his conversation when he misquoted God.
The wife ate. She gave the forbidden fruit to her husband, and he ate also.
That was the first sin in the Bible when the woman and then the man ate the forbidden fruit from the tree of knowledge of good and evil that was in the midst of the garden.
The first result of this first sin was a sense of shame and fear when the pair saw each other's nakedness. The couple immediately responded by the physical act of providing aprons for themselves made out of figs. They attempted to cover up their shame from each other. What the fig leaves couldn't cover was the internal part that was still seen by God. God dealt with the internal problem a different way.
The couple was banned from the Garden of Eden. The woman further would have labor pains during childbirth (Genesis 3:16). The man would have to work by the sweat of his brow for all long as he lives (Genesis 3:17-19).
Because the first pair disobeyed God's commandment, the entire human race received the same punishment.