Yeah, the example explains it like this:
"The following code lets you send strings like "90s" and "80w" to
position servos on pin 9 and 10 to 90 degrees and 80 degrees. You can
also use "d" to detach the servo on pin 10 and "a" to reattach it. Ok,
it is a silly program but it works for testing.
"
The thing you might not just magically know is that you send strings using the "Serial Monitor", it's the last icon in the toolbar at the top of the IDE. When you click it, the bottom of the IDE will change into an input box and a listbox. You can type things into the input box to send data to the Arduino and the listbox below it will print out anything the Arduino sends back. Here's a big tutorial on the serial stuff:
http://www.ladyada.net/learn/arduino/lesson4.html
Hope that helps!