So my wife thought it would be a nice suprise to swing by my LHBS and pick up something like when a girl gets flowers fro her man. Having gotten a bunch of stuff for christmas to start keging she got me this co2 charger, but I honestly have no idea how to use it. What's it for? I can't hook it to my kegerator and if I hook it to my gas in I have no idea the pressure I'm adding. Help.