The first few times you butcher it is best to focus on the basic process of killing the bird, plucking it and cutting it up. Don't worry about saving any of the organs until you get proficient at the rest of it.
Withhold feed overnight so there isn't much stuff in the intestinal tract. Make sure the birds have plenty of water so they bleed out quickly. (Dehydration prolongs the bleed-out process, which is traumatic for all parties involved.)
If you rupture the intestines it is not a disaster, because the poop washes off easily. Not so for the bile in the gall bladder.
The gall bladder is the little green thing attached to the liver. You will recognize the liver because it looks like liver. You will recognize the gall bladder after it breaks and gets green bile all over everything. It takes a LOT of washing to remove bile. You don't want to leave any traces of bile on the meat because it tastes nasty. Plus it may start to emulsify the fatty bits if you don't get it off right away. The gall bladder is the only internal organ you have to pay real attention to. And you only need to pay attention to it if you are trying to save the liver. Otherwise, just dump all the guts into the trash until you have more confidence in the process.
Seriously, in-person teachers for this stuff are hard to come by. If you don't have a teacher readily available, the best way to get started is to watch a bunch of videos, read a bunch of articles, and then DO it. You will make mistakes. You will learn from them. And you will eat well while you learn.