I took a course in college called Circus Techniques.
Juggling is not as hard as it looks. I found it was easiest to learn with bean-bags because they don’t bounce or roll away when you drop them. Also, start standing over a couch or bed, so you don’t have to bend down so much.
Start with one ball, tossing from one hand to the other with the ball peaking just above eye level.
When you can do this easily every time, try two balls, one in each hand. Toss with your strong hand first (right if you are right-handed, etc.), and when the ball hits it’s peak and starts down, toss with the other hand. The second ball should go up inside the arch of the first ball as it (the first ball) comes down. The rhythm will be toss-toss, catch-catch.
When you are solid with that, try it starting with your off-hand.
When you are solid with both hands starting, it is time to try three balls. Start with two balls in your strong hand and remember to toss the third ball. Once you get going your hands will make small circles, tossing on the inside and catching on the outside.
Stay loose and don’t try to grab the balls. Just cup your hand and let the ball fall into it. It might help also, to keep your eyes focused at the peak, and not follow the balls down. After that, practice makes perfect.
That is how I learned