Resource: Electric Potential, Electric Potential Difference, and Electric Potential Energy

The Physics Classroom:
Electric Potential  http://www.physicsclassroom.com/class/circuits/Lesson-1/Electric-Potential
Electric Potential Difference: http://www.physicsclassroom.com/class/circuits/Lesson-1/Electric-Potential-Difference
Electric Field and the Movement of Charge: http://www.physicsclassroom.com/class/circuits/Lesson-1/Electric-Field-and-the-Movement-of-Charge

Khan Academy: 
Electric potential energy: https://www.khanacademy.org/science/physics/electricity-and-magnetism/v/electric-potential-energy