Look up "chicken butchering" "chicken slaughtering" "chicken processing" etc. on youtube. Videos are the best way to learn. I also recommend one video in particular, titled something like "respectful chicken harvest". The video will start out with a lady talking about how she was brought this old laying hen and is known as the chicken lady, and soon she will sit down with the chicken on her lap, that's the right video. It's a useful video and the lady has an awesome attitude about the ordeal.
Some tips from my personal experience on certain parts of the butchering process:
A lot of people will tell you you need lung scrapers to get the lungs out or that they aren't very "easy" to get out. Personally I've found this untrue, my bird's lungs always come out pretty easily, you just have to get them right. What you need to do is get all the other organs out, then eyeball the inside of the carcass. The lungs will be two bright pink/red pockets, an inch or so big on an average-sized chicken, set deeply into the ribs, in the upper back. You need to stick your hand inside the carcass, and stick your pointer finger straight down on the top left edge of the lung. It should slip under the side of it, and go into the "canyon" between the ribs. Then curl your finger down and outwards and kinda scrape the lungs away from the "canyon". It should pretty much come up in one piece. Then you need to do this for the other 3-4 "canyons" of the rib, and once your have the whole lung away from the bone just give it a tug and you'll break the last connective tissues.
As for evisceration: People never really tell you HOW to eviscerate. They say "stick your hand in the bird, and pull the guts out!" But the thing is, the guts are all attached by hundreds of little strings of connective tissue. So what you need to do is open up the bird, and stick your whole hand in the opening. It'll go up, over all the guts and the liver. You'll feel the heart at the very top of the chest cavity, and there'll be a lot of little tight strings all around it. Just kinda grab at those and they should break somewhat easily. Keep moving your hand around inside the bird and try to break as many of these as you can; once you've got most of them, grab around the top of all the organs (heart should be right where your fingers meet you hand, and pull towards you. Once they're out on the table, you can take off what you want; heart, liver, gizzard, etc.
If you're going to be killing the bird with a killing cone method (or any method that doesn't involve taking off the head) it can sometimes be difficult to tell whether it's still alive or if it's just having "death throes". The best way to tell is by poking the eye. The eye of a dead bird won't react; it'll almost immediately begin to look glazed over. But the eye of a live bird will blink and move.
ALWAYS scald before plucking. I dry-plucked my first bird, it was god-awful. Scalded birds smell pretty gross, but it's SO much easier to pluck them.
