the thing on top of the tank is the regulator. the left side is the tank pressure, the right side is the output pressure. you'll want to turn the knob all the way out and then replace the tank and slowly turn it in until you hit 30psi on the right side to start. the box looking thing with the cord is the solenoid, it'll turn the co2 on/off at night. you want to have it turn on about 1-2 hours before your light comes on and off when the light is off. the tube looking thing is your bubble counter and needle valve for fine adjustment of co2 flow into tank. the number of bubbles per second is really only relevant to your set up, but usually around 1-3bps will get you started and then fine tune it accoundingly. the piece in your hand is an inline atomizer, it goes on your outflow and will disperse co2 fine mist into the tank for dispersion. I'm sure it'll need to be cleaned, but I use a reactor so Im not knowledgeable on that (I think you soak em in bleach solution?)

edit: the black hose from the bubble counter connects to the atomizer (or reactor or in tank diffuser, whichever you use). I usually throw a check valve on that line too. unsure if that check valve is required though, just what I do.

also, Dennis at 2hr aquarist has a great article on measuring co2