How do i change the desk top screen size?

I turned my computer on (Dell Inspiron 6000 laptop) and the desk top is square not wide screen how it usually is and there is a black border on the sides and the image quality isnt good now what do I have to change?How do i change the desk top screen size?
right click anywhere on desktop,properties. then go to settings and set the resolution up. or mess witl the buttons on monitor to adjust screen. i don't think the monitor went out of center more like comp resolution try that first.How do i change the desk top screen size?
id give you an answer if i knew
i want to know that hope someone tells you... is there a way to do that? i dont know
Go to your original Desktop where the icons are. Right click anywhere, but not on the icons. Select - Properties, and then Settings.
try right click on the background and go to properties and their should be some options.
click anywhere on desktop, right click, go to properties,and go on from there. I cant be the best of help because I have a vista running.
go to right clik on the mouse-properties-settings

or fro the buttons on the screen
go into control panel or right click on your desktop and select settings
try drop kicking it that should work then take a claw hammer and hit that thing till it behaves