The Hummingbird LEDs and motors are output devices. Scripts in Scratch send commands to these devices to make something happen. The Hummingbird sensors, on the other hand, are input devices. They send information to the Scratch program. The Scratch program can use this information to make a decision or control a light or a motor.
Find the most up-to-date information you need for using the Hummingbird Kit on their website
All of the sensors are attached to the Hummingbird in the same way. A sensor can be attached to any one of the four ports labeled “SENSORS.” Each sensor has a red wire, a black wire, and a yellow wire. The red wire should be connected to ‘+,’ the black to ‘-,’ and the yellow to ‘S.’
Check out Birdbrain Technology’s Programming with Scratch tutorial for more help