Have you done a physical exam yet? How old is he? Was he vaccinated for Marek's?
Your first step will be to separate him from the flock and placed into a cage, somewhere quiet and preferably warm.
If you haven't yet, you should do a physical exam to confirm a break or dislocation. These are generally quite treatable, although he may never regain full use of the wing - many times it will freeze up during the healing process. Thankfully, this doesn't generally affect the bird's daily life. There's also the potential for paralysis caused by Marek's Disease, though this is usually accompanied by leg paralysis so I would call that a somewhat less likely possibility.
If you do find a break or dislocation, you would do best to fold the wing against the body and wrap it in place (this is really a two person job - it should be secured around the whole body, over the back, beneath the good wing, and around the breast). If the injury includes a wound to the skin or muscle, you should first clean that using hydrogen peroxide and apply non-pain-medicated antibiotic ointment to the injury. You might also offer him ibuprofen to help with pain and inflammation - the dosage is (1) 200mg tablet, crushed, per two cups drinking water.
