Help request

I am trying to find out what ship and port my great-grandmother arrived into the Americas' on. Her name was Anne Larsdatter Kvissel, born May 1871 in Lomen Sokn, Vestre Slidre, Valdres, Norway. According to some family records she left Norway on 20 May 1891 (we don't know what port in Norway)bound for Decorah, Iowa where she arrived on 12 June 1891. Can anybody offer any suggestions on where to get some information? Thanks!!!!