please explain me the concept of electric potential and work done in a field. i am confused over it?take best example

							
Hi
The movement of a positive test          charge within an electric field is accompanied by changes in          potential energy. 
example : A gravitational analogy can be relied upon to          explain the reasoning behind the relationship between          location and potential energy. 
Moving a positive test charge          against the direction of an electric field is like moving a          mass upward within Earth's gravitational field. Both          movements would be like going against nature and          would require work by an external force. This work would in          turn increase the potential energy of the object. On the          other hand, the movement of a positive test charge in the          direction of an electric field would be like a mass falling          downward within Earth's gravitational field. Both movements          would be like going with nature and would occur          without the need of work by an external force. This motion          would result in the loss of potential energy. Potential          energy is the stored energy of position of an object and it          is related to the location of the object within a field.