I don't know of any links, however the basic technique is pretty simple. When you start out, it's best to use inexpensive throwing knives, because there's a good chance they'll get dented or bent when you first start learning.
First, take two steps away from your target, that'll give your knife about 1/2 a revolution in the air when you throw it. So hold it by the handle (properly released the blade should contact the target). Try not to throw hard when you start, just focus on what kind of revolutions you're getting. To throw, make sure the knife can slip easily from your hand, don't "snap" your wrist, just let it slide out. Bring your throwing hand to about ear level, and then pass your arm down quickly and smoothly to the target, the knife should slip out of your hand, make 1/2 a revolution in the air, and contact the target blade first.
When you start getting your form down, and begin to get good results, take four steps away from your target. Same throwing technique, only now the knife will make 1 full revolution in the air, go hold it by the blade. When you get good there, you can try different styles of release for intermediate ranges, and with practice judging how far you are from your target your proper release will become instinctive. Then you can work on adding more power to your throw.
Both Cold Steel and Hood's Woods have videos on the subject.