my family genealogy from norway

I am trying to find info on my grandmother. Born Sept. 10, 1893 in oslo. Her name on my dad's birth certificate is listed as Aagot Dagny Sather. she arrived in this country on the Franconia in Boston in 1912 and returned to Norway around 1919. she had and uncle Nils who traveled with her to boston and then he went on to tampa, florida. where can i turn for help in tracing her roots in norway