"R3" is a version. I assume you have the Arduino Uno R3 ?http://arduino.cc/en/Main/arduinoBoardUno
To change the firmware of the ATmega328P or the small usb-to-serial atmega, you have to be an experienced user. Don't even try that, it probably will make your Arduino Uno unusable.
What would you like to achieve ?
Do you want to control the radio with the Arduino ?
Or do you want to control the radio with the PC via the Arduino ?
Is the radio controlled by a serial port with logic TTL signal levels ?
In this situation, a SoftwareSerial port is used. The normal serial port to communicate with the PC and the SoftwareSerial port to communicate with the radio.
What you want is also possible (RX and TX to radio) and you can write a sketch that doesn't do a thing, so the ATmega328P doesn't use the RX and TX pins.
Can you write a sketch to the Arduino and see messages in the serial monitor ? That is only possible if the PC recognizes the Arduino as a serial port.
Also another serial port terminal program could be used.
Connecting to the radio uses that same serial port on the PC.