Walk up to a horse and press E. It stands still for you and you climb on from whichever side you are standing on. Look down and you see its ears, head and mane.
Ride with W and steer by looking. Shift steps up a gait (walk, trot, canter, gallop) and Ctrl steps down; Alt looks around without steering. A gallop is about 34 km/h, turns wide at speed and goes around trees rather than into them. E gets you off: the horse slows first and you step down beside it.
In third person you put your left foot in the stirrup, lean in over the saddle as you spring up and swing your right leg over its back before you sit. Getting off runs the same way in reverse.
