You don't need such a shield, but it might make things easier for you to build. My only concern on it is whether it supports in some manner a hook up to a separate power supply (battery pack or such) for use by the servos only. When you connect your servos (either with this shield or directly to the Arduino, which is easy), you should have them powered by a separate supply from the Arduino (rather than from the Arduino's regulator), because servos can use a bit of current, enough so as to cause a voltage sag and reset the Arduino (it won't harm the Arduino, but it can make debugging an issue a real pain). Regardless of how you hook them up, you would use the Servo library to control the servos.