Complex sentence: Born into a poor farming family in Mountcharles, County Donegal, he became a teacher, and in the 1890s began contributing articles and stories to newspapers in the US.
Split into simpler sentences: Born into a poor farming family in Mountcharles, County Donegal, he at first became a schoolteacher. He got started as a writer in the 1890s when he began contributing articles and stories to many newspapers in the US.