Hi,
hey i don't know how to interface a 16x2 LCD with arduino duemilanove. Coz i don't know where to give the voltage to the LCD panel. Plz guide me with this. I don't get the LCD illuminated even if I power it at the 3rd pin which is Vcc.
There is a software library here for the software interface to the LCD.
For the hardware connections, you need to check the datasheet for your LCD. That will tell you which pins need Vcc, GND, data lines, etc.
Thanx for replying.
now i m not able to get the datasheet of my LCD. can u plz give me the link? My LCD Panelhas a number JHD 162A on it.
Google is your friend 
http://pdf1.alldatasheet.com/datasheet-pdf/view/127934/ETC/JHD162A.html
The light in the LCD's doesn't use the standar LCD bus, they use alternate pins in each board. In your case, you have to apply led voltage to pins 15(+) & 16(-)
Regards.