Our local extension gave a chicken processing workshop back in June. My husband and I both attended and found it very helpful. Maybe your local state extension service has something on the same order. Ours also does one on harvesting goats (surprisingly popular farm animals here in central NH) and tried to offer one on processing rabbits, but ran into resistance on that one.
There were about 40 people in our class. I know you can find videos on You-tube and such, and I've seen pictures on various websites, but I learn better hands-on. The fellow who taught the class is a local farmer who does flock butchering on the side. He charges per 25 birds to come out, plus mileage if it's any distance. If you only have a few birds, I imagine it can get pretty pricey to pay someone else to do it.
I have to admit, I took the class because I wanted the first chicken I slaughtered and processed to be one I was NOT personally acquainted with. We're raising a mixed flock of dual purpose birds now, with 10 roosters destined for the freezer.
BTW, the class birds, all Cornish X, were free ranged at the farm next door to the class site - we saw them out in huge pens the day before, happy & healthy. Mine was one of the tastiest birds I've ever roasted - and the carcase made a wonderful stock.