Glider, I know it sounds confusing but it is really a neat trick to lower the supply voltage going to a device. The banded side of the diode is the cathode. As long as the anode is more positive than the cathode, the diode will be forward bias and will conduct. Because the diode has 1 silicone NP junction, a voltage drop of appox .6 volts will exist from that junction. Now if you like, you can just daisy chain junction after junction after junction and collect each .6 volt drop together as 1 big voltage drop.
Those Radio Shack diodes are 6 amps so you really can put a nice load on them with no worry at all. This trick works only in DC circuits. It's a quick, cheap & effective way to cut down a little or a lot of voltage going to a device.
I ran across the tip years ago while reading a book on "Electronic shortcuts and tips". It has helped me out of a jam a bunch of times.