This is a basic 3-ball cascade, the most basic 3-ball juggling pattern there is. If there is enough interest, I might post further patterns and tricks as people request them. You can also buy all kinds of juggling books which will guide you through these, but those cost money and most of us here are cheapskates. At least, I know I am.
I decided to use animated gifs on this to get the point across clearly and without distraction. All animations in this instructable were created using the Pivot stick-figure animator
Here's what you'll need:
1. 3 objects - preferably bean bags, but anything fairly spherical would work. I would recommend something with minimal bounce or roll, as you'll probably be doing a lot of chasing when you first start. For some good, sturdy, cheap bean bags, check out these.
2. A little space - Don't try to learn this in a phone booth. Chances are that you'll have smallish spherical objects bouncing off of walls at some point in this process, so you should move away from your grandmother's knick-knack shelves before proceeding.
3. Comfortable clothes - likewise, constrictive clothing will make your arm movements less fluid.
4. Some time - I learned to juggle 4 balls between classes at community college. I would hurry to my next class then stand in the hall juggling for 7 minutes before taking my seat.