Heracles is the son of Zeus and a mortal women. Hera jealous and angry with Zeus betrayer sends two snakes to kill Heracles. Heracles grabs each with one hand and chokes them to death.
Zeus wants to make Heracles immortal like him because he see's his son as the Greatest Champion. Hera hates Heracles because he represents infidelity and wants Heracles to die. They come to a agreement for Heracles to become immortal he must conqueror the 12 labors of Eurystheus.
Heracles grew up with great fame and married a princess. Euystheus afraid of Heracles power, demanded that Heracles do the ten labors but Heracles denied not wanting to become a servant. Hera then caused him to go mad and kill his own kids.
Heracles comes out of sanity and decides he will do the labors to forgive his sins. He does the first labor of which he will bring back the skin of the Nemea lion. Heracles club was useless against the lion so he backed the lion into the cave and choked him to death.
Heracles returned with the skin of the lion and the king said his next task was to kill the hydra. But with each head cut off it grew back two more. So, Heracles had his nephew Iolas burn the flesh where the head was cut off so a new head couldn't come out.
Heracles third labor was to retrieve the swift deer Tiryns who was the sacred deer of Artemis so he tracked it down for a year and caught it in a net.