Installing and running arduino uno

Hello,

I'm having a bit of trouble running a basic Firefly script in Grasshopper: "Firefly_00_Sensing." The "Ports Available" Component says that arduino is connected with com port 4. However, when I run FireflyUnoFirmata script in Arduino, it indicates that Arduino is connected with Com Port 5, and consequently there is no relationship yet between the Firefly script and Arduino. 

Perhaps this goes back the installation of Arduino driver. I followed all the steps listed in http://arduino.cc/en/Guide/Windows. However, firstly I do not see the ArduionUno Driver listed under Ports (COM & Lpt), instead the new driver after I plug ARduino in my computer,  is named "Communications Port (COM5). When I right click at COM 5 to update the driver according to the instructions, I cannot select the ArduinoUNO.inf file located in the drivers folder. I cannot see this file, only the FTDI USB Drivers" sub-directory.

Could you please help me with this? 

I have a Uno R2 board.

Please, let me know,

best,
Skender