you just reffer \extremeelectronics.co.in\ and read the AVR lcd interfaceing tutorial. you may download
the lcd.c , lcd.h, and myutils.h file and add source and header file to your main program and then you can easily use lcd as per your requirement.
But remember if you are going to use this source file keep one thing in mind you have to connect the datalines of lcd DB4-DB7 with 0-3 no. pins of any port. you have to use the first 4 bits of any portof mcu