Using an Analog Photocell with Arduino board

I have an analog photocell (make and model not known) which I am using with an Arduino board (DUEMILANOVE)

When I connect one terminal of the photocell to Analog Port 0 and the other terminal to 5 V and read off Analog Port 0, I always get a reading of 1023 irrespective of the surface (black or white) I am pointing the photocell towards.

When I disconnect the photocell, I still get readings which go down slowly. Is there something I am not doing correct here?

A photocell changes resistance depending on the amount of light hitting it. It must be used as part of a voltage divider. The middle of the voltage divider goes to the analog pin. One end goes to +V. The other end goes to ground.

Measure the resistance of the photocell under bright light, and in darkness. Choose a resister that approximately equals the larger value for the other half of the coltage divider.

Thanks a bunch. That did the trick