That's a big task. More and more books are being translated which provide more information. I would suggest a trip to the local library and a talk with the librarian. I know you can find books in the children's section; but if you wish to go more deeply, there is a surprising amount of information which has survived. Since, the Vikings were mariners and adventurers, you might find information about them via British, French, and any culture along the Western European coastline, as incursions and subsequent settlement was a pattern of their history. This explains settling of Iceland and trips to North America. How I taught my son was via mythology books. There is in our local museum a replica of a Norse Viking ship. If you have a Museum of Natural History in your community, you might be able to see dioramas from which you can glean much information on the tools, dress, and home life of the people about whom you are researching.