This throw is used against a straight punch.
As your attacker strikes, step forward and to the right slightly with your left foot and block the punch with a basic inside forearm block.
Twist anti-clockwise on the ball of your left foot and take your right hand behind your attackers back. Bend your knees slightly to pull youer attacker onto your back and place your right foot on the inside of their right knee.
As you straighten up to perform the throw, straighten your right leg to the side.