Complex sentence: The protests yielded little success, however, and so the Kollwitz and Kahlo founded the Guerilla Girls and embarked upon a campaign of postering actions throughout New York City, particularly targeting the SoHo and East Village, Manhattan neighborhoods.
Split into simpler sentences: The protests yielded little success, however, and so Kollwitz and Kahlo founded the Guerilla Girls group. Their first major action was to embark upon a postering campaign throughout New York City, particularly in the SoHo and East Village, Manhattan neighborhoods.