Short story here - an Italian detailed description may be downloaded: http://www.cesarebrizio.it/Arduino/HC-05.html
Inspired by an original sketch by TECHBITAR (HAZIM BITAR):
Noteworthy point: once the HC-05 is connected and a serial port is assigned, one can easily use the Serial Monitor of Arduino IDE to send and receive information. In other words, even though the Italian description suggests to use TeraTerm, that software is not strictly needed.
The project is extremely simple, and all that is needed is connecting an Arduino 1 to the HC-05 as illustrated in the fritzing schematics, then get your PC to recognize the HC-05 as an external bluetooth device and assign it a virtual COM port. Since that moment, Arduino can receive and send serial communications, that can be used to send commands and receive readings.