[header] How to put a head collar on a pony [title] Check that the halter (head collar) size fits the size of your pony's head. [step] If you go into a store that sells tack and horse supplies, you can ask an employee and they should help you find the right size. Make sure you have precise measurements of your horse's head before going in. 
Choose the halter that matches your pony's size. There are halters made specifically for horses, which are larger and ones made for ponies, which are smaller.