Ulkowski surname

I am interested in finding information about my acestors in Poland. My great grandfather was Marjan or Marian Ulkowski. He had three children, Ignatz, my grandfather, Michalina and Petonela. They came to the US in the early 1900s. My great grandfather remarried after the death of his wife, Antonette Czehulski????. He had other children but I only know of one son who lived in Lipno. My grandfather lived in Czarne. I was told it is in Northern Poland but cannot find any records of his name or the small village where he lived. I was also told that Lipno is about 15 miles from Czarne. Can anyone help me out with this? I thank you.