There are generally two types of boots, closed and open front. Open front are generally for jumping and closed are for cross country for more protection. Open front has two types Velcro and snap ons. Remember the buckles/ velcros go on the outside, so you can tell left or right that way. You slide the boot down until they fit snug around their cannon bone for the front legs and make sure it fits snugly on their hind legs too. It's kind of hard to explain with words. You can ask your trainer or someone at your barn to demonstrate. That's what I did when I was still learning. It makes much more sense when someone is there to show you.