Fully immerse the working (rear) blade vertically in the water towards the stern.
Keep looking forwards.
Keep your elbow on your hip to protect your shoulder.
The stern rudder affects the back of the kayak.
If your paddle is on the right and you want to steer towards the right, push the blade away from the stern. To steer towards the left, pull the blade towards the stern. Do the opposite when your paddle is on the left.
The stroke will become more effective if you drop the edge of your kayak on the opposite side to which you want to turn (edge on the left when steering to the right and vice versa).