Seperating him is the right first step. The others love to peck at blood so it was a perfectly natural response from them. If the wound is just a scabbed over area and prety superficial, all you really need to do is clean it with some warm soapy water like you would a wound on yourself. You can leave it to heal naturally, but definately keep him apart from the others until it's healed. If you need to put him back with the others, you can try putting on a bandage or putting some sort of ointment on the wound - many suggest using neosporin w/out pain killer (is toxic to chickens?), but I don't like to use antibiotic cream unless you know it's infected. I've used bag balm with a lot of success. It slows down healing somewhat, but tastes bad and will deter the others from pecking.
