When God created the Garden of Eden, he gave it to Adam and Eve.
But they screwed things up and God forced them to leave.
God told them not to eat fruit from the knowledge of good and evil tree or they would die.
One day Eve saw an evil serpent and it told her a lie.
The serpent said she wouldn't die and that she'd be like God if she ate from that tree.
She ate from it not knowing that she was being deceived.
She gave some of the fruit to Adam and he ate it too.
They disobeyed God which was a very stupid thing to do.
They knew that they were naked and that they had done wrong.
When they ate that forbidden fruit, their chance to live in paradise was gone.