The first problem is you are using Microchip's C18, not HiTech PICC18 Compiler.
The second problem is there is no lcd.c file listed under "Source Files."
You'll need to specify a device specific header file, <pic18f4550.h>, instead of <htc.h> and substitute appropriate delay routines in C18 for those used in the code for the PICC18 compiler.
It has become apparent that this is one of your first programs, if not the first, so I would suggest gaining experience with some simple examples, like blinking an LED, before tackling this project.
BigDog