Trying to find info on Baard Anderson's son

I am trying to figure out some information on the son of Baard Anderson. Baard was born in Norway January 8, 1840 the son of Anders Johnsen Kluken and Beret Bardsdtr. Before he came to America he had a son with a woman and the sons name was Seffanias or Steffen (not sure). I don't know the mother's name, but would like to find that out as well as Steffen's birithdate, place, etc. Baard came to America in 1869 and Steffen came with him I believe. Any help would be greatly appreciated!