Explain how this LED driver circuit will work - is there any way to turn on the LED?
It's not clear what the triangle with the circle is in detail, I suspect it's the output driver of a logic circuit (a microcontroller such as a PIC or AVR ?). If you can get the output of the driver to sink enough current and be at ground (0 Volts), the LED should light up.

If the circle of the output driver is meant to indicate negation, then you would have to set the input to logical 1 to switch the LED on.