According to several texts, here is a brief overview of Norse creation mythology.
** Note: There is, as with many types of mythology, variation between sources. **
It began with a giant chasm known as Ginnungagap (seeming emptiness). This primordial void separated Niflheim ("house of mists") and Muspell ("home of desolation"). Muspell was a place of eternal light and heat, so extreme that those who were not born there could not inhabit it. Muspell is said to be ruled by the fire giant, Surt, who guards the borders with his flaming sword. (Mythology tells us that Surt is the one who will set the World Tree on fire during Ragnarok ). Opposite of Muspell was Niflheim, a world of ice, darkness and cold. There are several rivers flowing through this area, many of which are frozen, that connect both Niflheim and Ginnungagap.
Eventually, the hot and the cold clashed. As the ice thawed and melted, one drop took form and became Ymir (seething clay)- the first of the frost giants. Ymir was a personification of the frozen ocean. Along with Ymir, another drop took form and became Audhumla (the nourisher), who was a gigantic cow. Four great streams of milk flowed from her teats, which supplied Ymir with the nourishment that he needed.
After satisfying himself, Ymir slept and from his armpits he produced a son and daughter. Then, one of his legs birthed a son, the six-headed giant Thrudgelmir. From this, all frost giants descended. Audhumla became to lick the salt off an ice block for nourishment. As she licked, her rough tongue revealed the hair of a god. After awhile longer, a whole head emerged from the ice. Eventually, she licked enough that Buri (the producer) was freed from the ice entirely. Shortly after, Buri begot a son named Bor (born).
When the giants became aware of Buri and his son Bor they began to wage a war against them, as Gods and Giants were representative of opposite forces: good and evil. This struggle continued until Bor married Bestla, daughter of the giant Bolthorn (the thorn of evil). She bore him three powerful sons: Odin (spirit), Vili (will) and Ve (holy). The three sons joined their father, as they had no use for Ymir and his brutish offspring. They attacked and defeated Ymir.
It is said that as Ymir sank down, blood gushed from his wounds and produced such floods that all of his race (with the exception of Bergelmir and his wife) perished. From Bergelmir and his wife, modern giants were born. Odin, Vili and Ve took Ymirs body to Ginnungagap. Out of the giants flesh they fashioned Midgard (middle garden) as Earth was called. The solid portion of Midgard was surround by the giants blood and sweat, forming the oceans. His bones made the hills, his teeth became cliffs, and his hair became trees and other plant life. Then the Gods took the giants skull and positioned it above the Earth and it became the Heavens. From his brains they fashioned clouds. To support the Heavens, the Gods stationed the strongest dwarfs ( Nordi, Sudri, Austri and Westri) at the four corners.
Then the Gods fashioned two chariots: one of sun and one of moon. They perceived Mani (the moon) and Sol (the sun) who were both children of the giant Mundilfari. His daughter, Mani, married Glaur (glow). Both brother and sister were transferred to the sky and began to guide their chariots along their appointed pathways. Some myths tell that both the Sun and Moon were pursued by fierce wolves, Skoll (repulsion) and Hati (hatred), who only wished to overtake and swallow whole the objects that radiated light so as to make the world dark once more. At times, it was said the wolves overtook their prey, thus producing eclipses.
The Gods now summoned Nott (night), a daughter of one of the giants named Norvi, and gave her the dark chariot, drawn by Hrim-faxi (frost mane). One of her children was a very radiant God named Dag (day). They provided him with a chariot as well, drawn by the white steed named Skin-faxi (shining mane).
One day, shortly after they created all of this, Odin, Vili and Ve were walking when they came across two uprooted trees. One was ash and the other elm. From these they created the first man and woman. Odin breathed the spirit of life into them. Vili gave to them wits, consciousness and heart. Ve gave them hearing and sight. They lived on Midgard and from them came the race of men.
And this is the creation story, via Norse mythology.