Newbie Multiplexing (I think) Help!

Other Hardware LEDs and Multiplexing
8

You don't need the analog reference at all if using as a digital pin.

signal_out = 14;

pinMode (signal_out, OUTPUT);

digitalWrite (signal_out, HIGH);
or
digitalWrite (signal_out, true);
or
digitalWrite (signal_out, 1);

will put out at a +Vcc signal (5V with a 5V supply) given that you have a proper current limit resistor

while
digitalWrite (signal_out, HIGH);
digitalWrite (signal_out, false);
digitalWrite (signal_out, 0);

will all bring it low, given that you have a proper current limit resistor

LEDs can be driven as shown here