There's two things needed - the OBD port reader and an app for your phone.
The OBD2 port reader is a BAFX product -
www.bafxpro.com
The reader was about $22 on Amazon.
The second part is the app. "Torque" is a free app for your phone that will display codes and PID gauges. There's also a "Torque Pro" version for about $5 that will enable data logging and some other functions. So far, "Torque" works just fine.