Some people consider this easier than the 3-ball cascade.
Step 1. Do two throws and stop. Throw on the inside (near the middle of your body) and catch on the outside. Hold one ball with your thumb, index, and middle fingers, and the other ball in your palm. Throw the ball in your fingers first and immediately after catching it, move it to your three fingers. Catch the second ball in your palm.
Step 2. Do three throws and stop. You will learn faster by doing short controlled runs rather than trying and failing to juggle continuously in Step 3. You can also try four throws.
Step 3. Congratulations, you are done! Now repeat from Step 1 using the other hand.