The EZ-Link will take care of the wireless data transmission, and the DHT22 is a sensor. The Arduino sits between the two, reading data from the DHT22 sensor and then sending the data to the EZ-Link module.
Before you start this section we suggest going thru the tutorials we have for both these components!
You then need to connect the power for the Bluetooth module: the 5V coming from the Arduino board, and the Ground pin.
Now, we have to make the connections from the Bluetooth board to the Arduino so that both can communicate via the Serial connection. Connect the Bluetooth TX pin to the Arduino RX (pin 0), and the RX pin to the Arduino TX (pin 1). You also have to connect the DTR pin of the Bluetooth board to the Arduino Reset pin (which is next to the 3.3V pin), via a 1uF capacitor (the negative side of the capacitor is marked with a gray line, and should be on the side of the Arduino Reset pin).
Finally, you need to plug the DHT temperature sensor to your project. Pin number 1 goes to the Arduino 5V, pin number 2 to Arduino pin 7, and pin number 4 to Arduino Ground. Finally, place a resistor (between 4.7K and 10K) between pin number 1 and 2 of the DHT sensor.
The following picture summarizes the connections for this project: