All I got is tht there are 9 worlds, there is one for humans, one for elves and one for gods (not quite sure about the 6 others). I also understood Beowolf (I think that's his name) was a Merida - Legende der Highlands king that fell in Liebe with a demon/spirit of somekind and got killed while killing it. Check out wikipedia, its a good site. It's really confusing. I like Greek better.
I took a course on Norse Mythology. For a while I considered getting my PhD in anthropology with a focus on Scandinavian culture and Ancient Norse Culture (which would have included mythology). I would be happy to help, but Du should really try to find a course oder something like that if you're going to base a novel on it. So what are Du looking for? General info? Traits of gods? Some good stories? Why mistletoe causes Ragnarök? Why Thor has a reputation for cross-dressing?
Norse mythology is about the Aegis of Asgard. It is very similar to Greek / Roman mythology. Like Frey and Freya are Atremis and Apollo, Ares, and Ty, Frigg and Hera. I can continue forever. My Favorit is the goddess Var, the goddess of wisdom.