Could be VGA. That's a quite common interface for a projector (it's seen by the PC as a monitor).
So it seems you need a USB-VGA converter (comes with the necessary driver).

Something like http://www.amazon.com/Multi-Monitor-External-Adapter-Graphic/dp/B000J4MT5Q

Or you need to run the application that you want to show on the projector on a device (laptop, PC) that does have a VGA-port. Might be cheaper if they happen to have one available.

Kees