Here are a few 3 ball lessons...
This is a video by Jason Garfield. Jason Garfield is considered one of the best jugglers in the world and is also a great juggling coach. Here he is breaking down the 3 ball cascade into it's most basic steps.
This trick has a few names, in this particular video it's called 'The Factory' but most GV members know it as 'The Machine'.
This is definately a tricky trick to learn. Be ready on the pause button, although this tutorial is pretty good it moves on very quickly.
I wouldn't usually recomend juggling videos from expertvillage (I find a few people are teaching tricks they struggle with or don't do properly) but here is a good tutorial for 'Nelson's Nemesis'.