Using ATTiny85 and USB for RF Transmitter [Help]

Hey, how can I create a small usb device that I can plug into my laptop (Windows 7) and then use it as RF Transmitter so that my Arduino with RF Receiver can receive it? Project details: I modified a broken RC Car, to control it from my laptop (using xbox controller :D) so I stripped the board out of it and using a hbridge I can control steering and speed. I'm using serial communication with just sending a byte for a command what to do. This is done by Serial communication (using C# as the controller System.IO.SerialPort). So I need to make this wireless and drive around :D So I thought I buy a RF Receiver/Transmitter pair and use that for wireless communication. But the problem I have is how do I transmit data? So I googled a bit and I came across: V-USB and a ATTiny85. And I think it is perfect but I don't know yet how to do it.. I mean how can I connect the usb with the ATTiny85? I really like this concept of the look: but then instead of the LED the RF Transmitter. But how can I burn my firmware on it that I can send the data I want and how do I read them from the computer? Am I able to use serial communication in C# (C/C++ isn't a problem either)

Thank you for reading :)