p.s. I am sure that it is evident that I got this code, or what is left of it from the Arduino Playground.
No, that's not evident at all. It wouldn't have taken you much time to add a link (Arduino Playground - HomePage for the benefit of others), so that we don't have to go and look for it.
LedControl.setLed() is already defined in LedControl.h, so you don't need to add a function prototype for it in your sketch.
Take a look at what your sketch is doing. Every time through loop it switches the leds on, waits for half a second, switches the leds off, then immediately starts loop again. The leds do turn off, but are turned back on again so quickly that you don't see it. Try adding another delay after switching them off.