It has this line, which I don't pretend to understand. I just used it as is and it worked...
Well this is fully explained but very carefully hidden on the Arduino site.
Start here: http://arduino.cc/en/Tutorial/LiquidCrystal
Scroll down to the bottom
Use the Liquid Crystal Library link to get here: LiquidCrystal - Arduino Reference
Use the LiquidCrystal() link to get here: LiquidCrystal - Arduino Reference
And there it is under 'Syntax'
Wouldn't it be easier if they completely documented the examples?
//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12); // put your pin numbers here
Don