Just a small point: The symbol you interpret as a "5" is actually a highly stylized "B," the logo for "Bachmann." It is not the model of the power supply. Look at the round logo at the right end of the words "BACHMANN TRAINS" at the top of this page, and you will see the same "B."
Hooking your track up to the AC side of the power supply can potentially damage the locomotive's motor. Hopefully you have not damaged the engine, but if it doesn't run when hooked up to the DC side and using the speed control, you have possibly damaged the motor. As ACY wrote, the AC terminals put out constant AC voltage (around 12 to 16 volts) and are used for powering switches and other accessories.
The DC terminals put out variable DC voltage (0 to ~12 volts) that is controlled by the speed control knob or lever. That DC power is what the locomotive works on.
For lots of free beginner information, go to the NMRA (National Model Railroad Association) website:
http://www.nmra.org/An introduction to model railroading is found at:
http://www.nmra.org/beginner/Links to information on trackwork, electrical, scenery, and lots more are found at:
http://www.nmra.org/beginner/consist.htmlBe certain to follow ACY's advice regarding not setting up on a carpet and cleaning the track.
Hope this helps, and welcome to a great hobby!
Happy RRing,
Jerry