Being able to juggle doesn't make you better than a non-juggler, or as I call them, nons. It does however make you a better juggler.
First thing you need to do is find some balls, 3 of them. You want something round that fits in your hand with a bit of weight. We use expensive custom made silicone balls but to learn something cheaper will work. Baseballs & oranges work well. Tennis balls are a bit light but a good choice other than that, you can add some weight to them by cutting a small slot in them and stuffing them with a dozen or so pennies. When I first started I filled them with dirt.
A couple of points before we start, try to stay relaxed & calm. Juggling isn't as fast as it looks. Also that circle pattern you see on cartoons and greeting cards is not the basic pattern, you'll be tossing balls in a figure 8 pattern.
1 Ball
First let's try tossing one ball back & forth from hand to hand. Toss the ball about as high as your head and aim it so it lands perfectly in your other hand without having to reach for it. Jugglers aren't so much great catchers as great throwers. If the throw is accurate the catch will be effortless.
Notice every throw from both hands gets tossed up in the air. Make sure you don't simply hand off the ball to your first hand, each toss should go up a foot or two.
2 Balls
The throw you just learned is the only throw you need to juggle 3 balls, you just need to make more of them. Start with a ball in each hand. Once it gets as high as it's going to go throw the second ball, then catch the first, then the second. Make sure each ball goes just as high as the last throw. Also make sure you don't throw the balls at the same time, you want to wait till the first one is just starting to come down before the second toss.
Make sure you can do this starting with either hand, practice right/left for a while and then get comfortable with throwing left/right.
3 Ball Flash
The next step is adding the final ball. The first thing to master is the Flash or 1 throw and catch with each ball.
Put 2 balls in your best hand. Those will be throws number 1 & 3. Your other hand will have one ball, throw number 2. Using the same kind of throws from the one ball exercise and the same rhythm from the 2 ball exercise, gently and calmy make the throws 1, 2 & 3 and let the balls fall back into your hands.
Once you get this try it starting with your other hand.
3 Balls continuous
Once you have the flash mastered starting from either hand the next step should be obvious, don't stop. Instead of 3 throws make 4, then 5...