Tracing Swedish Family (Ostman)

[Ostman family Julie Edser]

Hi, My name is Julie and I am trying to find information about my Grandfather Johannes Evert Ostman born 1902 in Stockholm, Sweden but was told he was register in his parish in Finland. His mother's name is Anna Kristina Ostman and father Andres Herman Ostman, we think his father may have been from Sweden. I have tried everything so if anyone out there could lead me in the right direcetion I would be greatful.  
I hope I have submitted this right.