Complex sentence: Marshall Ganz returned to California and worked for many years on the staff of the United Farm Workers, later taught organizing strategies, and in 2008 played a crucial role in organizing Barack Obama's field staff for the campaign.
Split into simpler sentences: Marshall Ganz returned to California, where he worked for many years on the staff of the United Farm Workers. In 2008 he played a crucial role in organizing Barack Obama's field staff for the campaign.