Another great chapter from the Parallax documentation for the Board of Education shield bot kit for Arduino! Chapter 2:
In this chapter, you will use the Board of Education Shield for building and testing circuits with Parallax continuous rotation servos, resistors, and light-emitting diodes. Along the way, you’ll start learning the basics of building circuits and making the Arduino interact with them. By the end of the chapter, you’ll have a pair of servos connected, each with its own signal indicator light, and you’ll be writing sketches to control servo speed and direction.