Ideas on finding family in Norway

Hello -

My great great great Grandfather came to the USA from Oslo, finally settling in Winona, MN. I have a good deal of genealogy info on my family in the USA however no family here knows any family in Norway. I wanted to post and request ideas and genealogical referrals or ideas to help us bridge the divide and make the connection back to family across the pond. I want my children to be connected to their roots more than we are now. I'd welcome your perspective and thank you in advance.