Which Kindle model do you have?
Do you see the Serial Number on the back?
In terms of how they look:
Kindle 1: has a “roller wheel” on the right-side that moves a silver square up and down a line
Kindle 2 (could be US or International…they look the same from the outside): has a “joystick” type controller in the bottom right corner as you face the screen
Kindle DX (could be US or International): larger screen (9.7″ versus 6″). Next and previous page buttons only on the right side as you face the screen
Kindle 3 (could be wi-fi only or wi-fi and 3G: also has a European variant): has a square with a ridge surrounding it in the bottom right corner as a directional device