Javascript Inheritance: Can some one tell me step by step how i'd make...

...javascript constructors that uses? Inheritence

A company is to model its employees and customers as a collection of JavaScript
objects. Provide a sketch of the object constructors for the following:
A Person has a name and a unique identifier. A Contact is a Person with
a phone number, email address and area code. A Customer is a Contact
with one or more past orders. An Employee is a Person with a salary and
department. A SalesPerson is an Employee who is in charge of sales for
a number of products in one or more areas.

plz help im so confused here!