Where do I change the first name of the city I put in the address field of my MacBook Pro in June 2009?

When I finally got my MacBook Pro 15 in June 2009 I tore it open and began hastily setting it up. In my haste, I accidently chose a town or zipcode town 20 miles north of me as to where I live. Unfortunately, when there are specials in that area, or something is happening that I might otherwise be interested in...I am not because a 20 mile drive here seems like an eternity. Can someone tell me how to change the city in the original set-up and where it is stored so that I might change it to reflect my true city.

Thank you,

Jim