Let me put your assignment in some sort of context:
Social contract theory is the view that persons' moral and/or
political obligations are dependent upon a contract or agreement among them to
form the society in which they live.
Social contract theory is given its first full exposition and
defense by Thomas Hobbes. After Hobbes, John Locke and Jean-Jacques Rousseau
are the best known proponents of this enormously influential theory, which has
been one of the most dominant theories within moral and political theory
throughout the history of the modern West.
http://www.iep.utm.edu/soc-cont/
So what principles would you suggest we accept, what form
would your social contract take and what would be the role of government in
your model?