James Christian Larsen

So I am researching my great-great grandfather. He was born June 14, 1860 in Tromso, Norway. I have been able to discover that he was a blacksmith's assistant in 1875 in Tromso, Norway and that his name was Jens Christian Larsen. He emigrated to the United States in 1880 or 1881. His wife's name was Anna C and they lived in Wisconsin. I want to go back further but I am having difficulty doing so. Any help or suggestions would be very much appreciated.