Safety stirrups usually have an unlocking mechanism or an open side - that side should always be pointing outward when your foot is in the stirrup. So, the open side should be closer to the knee pad of the saddle after they have been attached.

What is the correct way to wear stirrups?

Put your toes through the smaller hole, the strap or “stirrup” under the arch of your foot, and put your heel and ankle through the larger hole at the back of the stirrup. Pull the stirrup up to just under your knee—you don't want it to hinder movement by constricting your knee.

How do you know if a stirrup is left or right?

Similar to a jockey, they ride above the action of their horse, perched precariously out of the saddle. To find the correct stirrup length, sit in the saddle with your feet out of the irons. Relax your leg and allow the stirrups to bump against your feet. The bar (bottom) of the stirrup should hit your ankle bone.