Using the Modulation Toolkit, you can generate a QAM modulated signal. It looks like there is a basic example which simulates QAM modulation and demodulation. In it, a JPG image is converted to a binary bitstream. This bitstream is then modulated onto the chosen carrier sine wave frequency. This is a basic example, and will require some work to adapt to your application.
This looks like your best starting point for what you are trying to do. I also encourage you to look at the examples that ship with the NI-RFSG driver and the Modulation Toolkit. You can view these for LabVIEW in the Example Finder (LabVIEW » Help » Find Examples » Hardware Input and Output » Modular Instruments » NI-RFSG).