Worm casting collection process

I wanted to try out worm casting as fertilizer for my fruit trees. I want to stick with natural organic material.
So we visited a worm farm to pick up some worm casting. The gentleman at the farm was kind enough to explain the process to my critters; my daughter was grossed out by the worms but my son enjoyed the tour.

If you have tried it share your experience and methods how you apply worm casting, in the comments. I applied it around the drip line and watered.