Horses are mobs introduced by Mo' Creatures. They must be tamed by feeding them wheat, bread, or an apple. It only takes one apple to tame a horse, no matter what kind, but the amount of bread and wheat varies depending on what horse you are trying to obtain. After that, they can be ridden if they are saddled. You can make a saddle out of five leather and three iron bars, if you find a saddle from a dungeon, just add one iron bar underneath it.
On a pegusus though you may put a rabbit on your head which makes you fly extremely fast. However if you only have a regular horse you need a mouse in your hand. But on the horse it is very easy to lose control. On pegusus this glitch makes transportation very quick and useful. But there is a downside to this, if you use the rabbit pegusus combo you may not be able to see your horses name or health anymore and when flying a pegusus to make any progress upwards without runing into everything you need to be completely stopped.