Since you don't have any details yet, I suggest you check out this web site for ideas on how to proceed:http://www.rootsweb.com/~wgnorway/rtips.htm
Look for clues in documents that are listed on that web site (vital records, church, emigration, naturalization, etc.) You need to know more - like where he came from or was born, his "real" name, etc. You'll find that through some sources in U.S. records - it may take some digging, but I'm sure you'll find it rewarding. Exhaust the U.S. sources before trying to find anything in Norway.
As I indicated earlier, I found information on Severt's son's wife and her ancestors. But it's impossible to match up Severt Swanson/Swensen, b. 1866 somewhere in Norway. Keep in mind that his name in Norway probably was not Swansen or Swensen ... and in fact, if his father's name was Ingebright, his name was probably Severt Ingebrightsen from ?? farm. And based on the father's name, his grandfather would have been named Sven (xx-sen) (farmname). The surname they used changed every time they moved to a different farm. If you look over the information I gave you about the Rognes family, you'll see that Anders Andersen Rognes, b. 1822 was originally called Anders Andersen Soknes, because he was born at Soknes. I know that if I look up the Soknes farms, I will probably find more family history about Anders Andersen there. (And I can tell that his father was named Anders too.)
Hope this is of some help.