Need help - send audio to Bluetooth via USB adapter (Blind)

I could use some help. I have a blind friend who uses her computer a lot. She is a school teacher and uses her computer in the classroom. She has a program that "reads" the screen, and sends that audio to the computer speakers.
What she would like is a way for the audio to go to a Bluetooth headset instead of the computer speakers. Then she could listen without the students hearing / being distracted, etc. With it being wireless, she could be about the room and still be listening.
I purchased an IOGEAR GBU321 USB adapter and a Plantronics Explorer 233 headset, got them "paired", but now I'm stuck. How do I get the audio to go to the USB adapter instead of the speakers? Or do I need different hardware?
Sorry I'm not too sharp on all this, and my friend is very handicapped. Any help will be much appreciated!