Here is the definition of Joule (http://en.wikipedia.org/wiki/Joule):
"It is the energy expended in applying a force of one Newton through a distance of one metre (1 Newton·metre or N·m)."
Here is the definition of Potential Energy (http://en.wikipedia.org/wiki/Potential_energy):
"Potential energy is the energy stored in a body or in a system"
All you did is rearrange the original statement, you need to use the definitions (I recommend reading the wiki pages) to come up with a definition of the original statement.