Complex sentence: On March 4,1840, Wolcott and Johnson opened the first commercial portrait studio in the world for taking pictures of people that would sit for their likeness to be captured on a permanent median for future viewing.
Split into simpler sentences: On March 4,1840, they opened the first portrait studio in the world as a business for taking pictures of people. They would sit for their likeness to be captured on a permanent median for future viewing.