Fellow Newbies: I find this helpful.ARDUINO_NOTEBOOKv6.pdf
Recently in + CODE inbetween Category
The arduino homePage links to tutorials that introduce the switch as an INput that sends a signal to the arduino which you can then program to affect an OUTput such as the led.
Limor Fried's tutorial # 5 introduces the switch as an INput into the arduino. She provides the basics that will help you to successfully include a switch and provides as much technical background as well.
IN + OUT