WASHINGTON — Two weeks after President Barack Obama signed the big health care overhaul into law, Americans are struggling to understand how — and when — the sweeping measure will affect them. Questions reflecting confusion have flooded insurance companies, doctors' offices, human resources departments and business groups. "They're saying, 'Where do we get the free Obama care, and how do I sign up for that?' " said Carrie McLean, a licensed agent for eHealthInsurance.com. The California-based company sells coverage from 185 health insurance carriers in 50 states. McLean said the call center had been inundated by uninsured consumers who were...