Well, I did a little searching on Google.  I wasn't too successful because most of what I found was in Finish.

However, I did find one explanation of the creation in the Kalevala:  "After a preamble by the bard, he proceeds to relate the creation myth of how the Virgin of the Air descended into the sea, where she is fertilized by the winds and waves and becomes the Water-Mother. A teal builds a nest on her knee, and lays eggs. The eggs fall from the nest and break, but the fragments form the earth, sky, sun, moon and clouds. The Water-Mother creates bays, sea-shores, and the depths and shallows of the ocean." 

The site does explain that "In the Kalevala, magic is made by chanting special runos. These runos often petitioned gods or spirits, or spoke of origins. … According to the ancient beliefs, anyone could use the magic runos, but great magicians like Väinämöinen knew more runos and more powerful ones than common people did. Another belief was that the spell created by a runo could be undone by singing the words in backward order."

I don't know how accurate this site is, but it sounds like songs/chants are the source of magic in the Kalevala.  Although it doesn’t sound like song was used exclusively in the creation of the world, it would be central to any spells that helped shape the world.

Thanks for pointing this out.