Use the straight right after you have set up an opening with your jab.
Step 1:
After establishing your stance, shift your weight to your left leg. Pivot your right (rear) foot so that your toes are pointing forward, while simultaneously delivering a right punch. Remember to push against the floor with your rear foot. (At the very last moment, rotate your fist so that your thumb is facing the floor.)
Step 2:
Pull your hand back on the same plane the punch was thrown. Return your rear foot to its original position-toes pointing between 12 and 2 o'clock.