RE: Newbie here, how does it all work?
The simple solution for a BB caliber gun is one form [link=http://www.swampworks.com]swampworks[/link] or [link=http://www.battlersconnection.com]Battlers Connection)[/link] .
If you want a little nicer gun, and want rotation, you might consider going 3/16" and getting a gun from the [link=http://www.users.qwest.net/~rcwarship/weapons.html]Model Armory[/link].
All of these use co2, and require a regulator. Several nice ones are available form Palmer Pursuit (paintball hardware). For wiring these there are lots of sources of information. You might want to start with [link=http://www.ntxbg.org]The North Texas Battle Group[/link], as we have some tips you might want to see, and links to other groups for further information.
Good luck, and welcome to the obsession. Remember, though, that the guns are dangerous and can and do create damage. Always wear safety glasses, and have anyone in the area don them as well.
Wreno
NTXBG