Welcome to BYC!
First, it would be helpful to know how many and what breeds of chickens you are ordering. Is the coop all set up with bedding, waterer, feeder? If you are getting day old chicks you will need an area that is draft free with a good light, like a clamp-on light with a reflector, for warmth. You will be able to tell if the chicks are too hot or cold by the way they act. If they all cram under the light or in a corner they are too cold and will suffocate each other. If they stay away from the light and have their beaks open like they are panting they are too hot. Just lower the wattage of the light bulb you are using. You will need bedding, most folks use pine shavings available at your local feed store, but put paper towels over it for a few days until the chicks learn that chick starter is food and not the shavings. Once they're eating their feed well you can remove the paper towels. You'll need a chick waterer up on a piece of wood or brick or something to keep it from filling up with shavings quite so badly. A chick feeder. These you can also get at the feed store. You'll need chick starter for feed. And if you are ordering chicks through the mail, it would be wise to also pick up a pack of vitamins with electrolytes to give them in their water for a week or so. When they come, you'll need to watch for pasty butt, when their poop sticks to their downy feathers at their vent and causes them to not be able to poop correctly. This will have to be cleaned off with a warm damp rag often though this usually stops after the first week.