This is how I hold the spoon underneath the quilt sandwich which is not taught in the hoop.The purpose of the spoon is to create a ridge for the needle to glance off.
Here you see it being pushed up in front of the needle to create that ridge. The spoon is moved back towards the needle. The tip of the needle hits the spoon, you can feel it.
The needle is balanced back as in rocker quilting to push the needle forward off the ridge of the spoon. Once the needle comes through to the front, the spoon is relaxed and moving forward in the same moment to put the needle back into the quilt sandwich. The spoon is again moved back and up to create the ridge again.
Essentially, the spoon moves forwards and back, forwards and back while rocker quilting. The spoon is the substitute for the index finger underneath. There is a rhythm to it and like anything I guess it's practice. It didn't take me too long because I was already using a substitute for my finger underneath. All these photos are able to be clicked on for the close ups.
Jinny Beyer has some information here as well.