This is an excerpt I found online about Tylan shots, but it gives pretty good instructions:
Tylan injectable can be given intramuscularlyin the breast muscle, sub cutaneously OR can be given orally. To inject it, draw the drug out of the bottle, using a 25 gauge needle (tylan is fairly thick and won't go through a needle much smaller than 25 gauge). Find the breast muscle on either side of the keel, below the crop but above the abdomen. Dab the spot you're going to inject with alcohol or iodine (preferably alcohol so it doesn't stain the feathers) and, with the syringe attached to the needle, poke the needle straight in to the muscle. Draw back on the plunger of the syringe to make sure you're not putting the drug in a vein, as this would be bad! Then, administer the dose, pulling the needle straight out when done and pressing a clean swab to the hole to make sure it seals properly. THere shouldn't be any (or very little) blood. To give subcutaneously, you can lift a tent of skin at the back of the neck and inject just under the skin (again drawing back on the plunger for blood- don't want blood!) OR you can inject tylan into the little pocket of skin where the wing meets the body- convenient little pocket there too. The drug can also be given orally, but DON"T use the same syringe to give orally as you do to draw the drug from the bottle or you will risk introducing bacteria to the bottle, which is supposed to contain sterile drug. Transfer the tylan to another syringe, then I like to draw up some babyfood (like blueberry puree or something sweet) to hide the taste as it tastes pretty gross. Give orally.