As far as the drivers go, you can get them from http://www.ftdichip.com/FTDrivers.htm
but when you plug the USB cable into your computer, it should show up under your Device Manager as a COM port. When you setup the Renesas flash developement software you select the proper COM port and then continue with your flashing.
After you get that set you should see this.
If you're still having problems post some screen shots of the error you're getting.