The main important event in Genesis chapter 9 is that God made a covenant with Noah. The first thing that happens is that God gives Noah and his sons the responsibility of reproducing. Next God said that he would never cause a flood that big again. Finally God created a rainbow to show his faithfulness and love.
"God blessed Noah and his sons and said to them: Be fertile and multiply and fill the earth. Fear and dread of you shall come upon all the animals of the earth and all birds of the air, upon all the creatures that move about on the ground and all the fishes of the sea; into your power they are delivered" (Gn 9:1-2)
"I will remember my covenant between me and you and all living creatures of every kind. Never again will the waters become a flood to destroy all life" (Gn 9:15).
“Whenever the rainbow appears in the clouds, I will see it and remember the everlasting covenant between God and all living creatures of every kind on the earth” (Gn 9:16).