Step 1: Fit the Top Strap

Unbuckle the harness and place it over your dog's head with the front strap facing towards you.

Adjust the top strap so the O-rings sit above and behind your dog's shoulders.
Step 2: Fit the Bottom Strap

Adjust the bottom strap until you can only fit 1-2 fingers between your dog's body and the harness.
Step 3: Fit the Front Strap

The front strap should sit horizontally and the d-ring should remain in the center.
Now, enjoy your walk :)