There are three levels in which nine worlds reside.
The upper level :
Asgard the realm of the gods.
alfheim the realm of the elves.
The Middle level :
Midgard the realm of men (where we are)
Jotunheim the realm of the giants.
Svartalfaheim the realm of the dark elves.
Nithavellir the realm of the dwarves.
The Lower level :
Muspelheim The realm of the fire, a flaming southern region.
Niflheim the realm of the dead, represented as ice.
All of this is held together by the great world tree,Ygdrasil. But it has not always been this way. In the beginning there was a great chasm (Ginnungagap) seperating the worlds of Niflheim, and Muspelheim, (fire and ice). When fire and ice met, they combined to form a giant, named Ymir, and a cow, named Audhumbla, (Auðhumla) who nourished Ymir, while she survived by licking the salty ice blocks. From her licking emerged Bur (Búri), the grandfather of the Aesir. Ymir, father of the frost giants, employed equally unusal procreative techniques. He sweated a male and a female from under his left arm.
Odin Kills Ymir
Odin, the son of Bur's son Borr, killed Ymir. The blood pouring out of the giant's body killed all the frost giants Ymir had created, except Bergelmir. From the Ymir's dead body, Odin created the world. Ymir's blood was the sea; his flesh, the earth; his skull, the sky; his bones, the mountains; his hair, the trees. The new Ymir-based world was Midgard. Ymir's eyebrow was used to fence in the area where mankind would live. Around Midgard was an ocean where a serpent, Jormungand, who was big enough to form a ring around Midgard by putting his tail in his mouth, lived.
From Ymir's body grew an ash tree named Ygdrasil whose branches covered the known world and supported the universe. Ygdrasil had three roots going to each of the three levels of the world. Three springs supplied it with water. One root went into Asgard, the home of the gods, another went into the land of the giants, Jotunheim, and a third went to that primeval world of ice, darkness, and the dead, known as Niflheim. In Jotunheim's spring, Mimir, lay wisdom. In Niflheim, the spring nourished the adder Nidhogge (darkness) who gnawed at the roots of Ygdrasil.
The Three Norns
The spring by the Asgard root was cared for by the three Norns, goddesses of fate:
Urdur (the past)
Verdandi (the present), and
Skuld (the future).
This has been a brief overview of the creation of the world, enjoy.
More on the way of the warriors later.....