The main idea is God blessed Noah and his sons and said to them” Be fertile and multiply and fill the earth" God created a covenant with Noah to never flood the earth again. To remember this promise he made a rainbow after it rained to remind Noah that God will never create a "flood to devastate the earth". This rainbow will also remind God between the covenant every living creature and every mortal being. Noah got drunk and his son Canaan didn't help him so he told his brother’s Shem and Japheth. Since Shem and Japheth were the only ones who helped his father Noah cursed Canaan. With this Curse, Canan was the slave of his brothers and God.
The first thing that happens is God blesses Noah and his sons and says to them "Be fertile and multiply and fill the earth" The first thing that happens is God blesses Noah and his Sons. He also says that any living creature will be there's to eat and the only thing they cannot eat is meat. (Gn 9;1-5)
Next God then created a covenant between Noah, every living creature, and every mortal. God said to Noah “I will establish my covenant with you, that never again shall all creatures be destroyed by the waters of a flood; there shall not be another flood to devastate the earth”. Gn 9;11
Finally, God said to Noah “I set my bow in the clouds to serve as a sign of the covenant between me and the earth. “When I bring clouds over the earth, and the bow appears in the clouds, I will remember the covenant between me and you and every living creature and every mortal being”. Gn 9;13-15
A life lesson we can learn from this chapter about God's Covenant with Noah is when we human beings keep multiplying we should continue to fulfill in being God’s image and let the rainbow remind us to part away from sin to prevent ramification.