Arduino has a Servo library which allows to control servo motors. Today we will use the following small servo motor and write a program, which read a angle value from Serial port and rotate servo motor according to it.
Compile and upload above code to Arduino, then connect control pin(gray wire) of Servo motor to Arduino pin 11, connect black wire to Gnd of Arduino and red wire to +5V. This is how it looks:
And this is a video demonstration of moving Servo 0 -> 90 -> 180 -> 0 -> 90: