Czerwinski

I am hoping someone can help me with some information.I am researching my great grandparents and I'm having trouble finding information.They are Adam Czerwinski and wife being Eva ( maiden name unknown ) I know they were both born in Poland, the immigration year for Adam is 1899 and Eva is 1901.How does one find information on the immigration such as what ship they were on, where they came from, etc.?I have found them in the 1920 census living with they're oldest son and family and found them also in the 1930 census living with my grandfather and his family. In 1920 they were living in Mason Twship (Arenac co.) and in 1930 they were in Detroit.I'm curious to know if any one out there would have any information on any "Czerwinski".Any help would be greatly appreciated.
Sharron - slkhommie@aol.com