TechDepot Egypt @ instructables.com has published a tutorial on how to connect a HC-05 Bluetooth module to Arduino. Turorial shows how to connect the module with Arduino and example code is included.
It is worth noting that the HC-05 power in (Vcc) uses 5V, while the transmit and receive (TXD and RXD) logic signal uses 3.3V. Accordingly sending signals from the HC-05 module to Arduino is ok as the Arduino I/O pins can safely receive up to 5V but the issue is when Arduino tries to send the data to the HC-05 with signal level 5V, in this case it is required to use a voltage divider as we will see during the tutorial.
Connecting HC-05 Bluetooth Module to Arduino – [Link]