You'll want to use the LiquidCrystal library. A nice tutorial has been setup here:http://www.arduino.cc/en/Tutorial/LiquidCrystal
I should note that the library has been updated but it is not included int the 0016 package, you'll have to manually update the library yourself (drag and drop files, it's easy).
I would not recommend using the old LiquidCrystal library as it has timing issues that were never addressed until recently. I've used both and the new library is a little slower but about 100 times more reliable. The old library has been known (and i've personal had it happen) to throw garbled text on the screen or not putting text on at all.
It's a good tutorial with good examples, give it a look over.