Joseph had dreams of greatness. Joseph was the oldest son of his father, Jacob's favorite wife, so Jacob gave Joseph a special robe and the birthright. His brothers were jealous about his special gift and how he was favored by their father, they all wanted to do something about it.
20 pieces of silver
How much do you want for him
Judah one of the older sons wanted to kill Joseph, but Ruben the oldest of all the sons saved him and instead they decided to put Joseph in the pit.
Once Ruben left, Judah decide to sell Joseph to a Egyptian servant called Photiphar who worked for the Pharaoh who was the king of Egypt.
Judah sold Joseph to Photiphar for twenty pieces of silver.
The brothers didn't want to tell their father that they sold Joseph, so they got Joseph's robe and put goats blood on it to make it look like Joseph was dead.