If you liked that we can add a few more details:
Position 1: Step forward with your right foot in front of the partners' right foot. Your
knee is bent and
weight is on your right foot toes. If you do not bend your knee your kuzushi won't work. You'll know that if you feel that your opponent is heavy and you have to use force to throw. If you put weight on your heel you won't be able to turn enough and you will feel that parthers leg that you trying to pick is far away.
This first step does not use any muscle power. Just move your foot.
Position 2. With your left foot step behind your right foot. Again,
knee bent and
weight is on your toes. Your right thigh should be touching your left leg. Left foot now points to the same direction as your partner's feet.
If your feet are far apart after first step you screwed Position 1.
Position 3. Kuzushi. Your right hand comes to your shoulder as if you are trying to lift a kettlebell. Your
left elbow is up and hand is parallel to the ground. Your knee is still bent! You should have feeling that opponent is high above you and you are trying to get under him. Now you turn your head and shoulders and put all your weight on your left foot. Your partner is in the "kuszushi" position that I described before.
At this point you should be able to stand on your bent(!) left leg and move your right foot anywhere you want. If you have to put weight on you right foot to be balanced then move your left foot wherever it feels stable.
An advanced tip: Your right hand twists inward and left twists outward. This helps killing the slack in the gi.
Position 4. This is straightforward. You bend forward while keeping your right leg in front of your partner's leg. If you did all steps before correctly you won't feel any partner's weight. If you are especially good you will remember to point your right foot toes down to tense up right leg and this will send partner high in the air.
Typical beginners mistakes:
Making first step too close: Your butt should not be touching the partner. If you touched you stepped too close.
Not bending knees: The feeling is that opponent is below you.
Flat footed: You start turning your body and your knee is twisting.
First step on a wrong spot: you cannot lift your right foot in position 3.
Too much slack in the grips: You turn your head and shoulders in position 3 and opponent does not come into "kuzushi" position.
Gripping with all five fingers instead of three: partner is heavy. You cannot get under him.
Dropping your left elbow: The throw works, but it's a crappy throw feeling. Cannot explain.
Using force and speed: When you do the throw imagine that your partner is 5-year-old kid and you do not want to hurt him. This is how much force should be necessary for the throw. Make pauses as you move from one position to another and adjust your body before the next move.