Romans 3:23 is where most people agree the Bible defines sin. It portrays sin as the opposite of the Glory of God, and that it is any action which goes against the Glory of God. As for the punishment of Sin, Romans 6:23 stats the death is the only suitable result for sin via a metaphor of wage earning. It likens death to a paycheck for sin.
The first recorded sin in the Bible
The first recorded sin happened in Genesis 3. Satan disguised himself as a snake who could speak which taunted Eve about God's rule against eating the fruit of the tree of knowledge. After convicing Adam to partake in this sin of tasting the fruit, God confronted them and punished them, the most significant being the penalty of death for man.