I just installed it and I'm at a loss. Any advice?
Go to Control Panel > Hardware and Sound > Sound
Right click your headphones in the list and click set as default.
You do the same thing to get it set back to your speakers by setting them as default.
If you can't see them in the list you need to click on an edge of the list and select show disabled/disconnected devices.
In the event this doesn't work there is something else wrong I'd need more details for.