use of the signal wire in "prototype breadboard"

MarkO, very interesting. You managed to answer everything BUT what I asked. I didn’t ask about the programming side. I didn’t ask for an LED circuit. I asked how the signal wire is used, how it acts in a circuit, and where it would be placed in a non-breadboard application like the one shown in “prototype breadboard”. I tried to make it clear that the only part I don’t understand is the signal wire. I have a little experience with breadboards, but none of my experience has dealt with incorporating a PWM line into a circuit.

MarkO, please let someone else answer my posts.