The theory is that if you wound a plant stem it will under the right circumstances try to grow new roots. Once the roots grow , you cut below the root area & transplant somewhere else in the garden,
I cut a circular cut around the whole stem then another cut below it approx 3-5 cm below it. Then a vertical straight cut from the top cut to the bottom then started to remove the bark & cambium.
Hopefully within a few weeks it should start start to root. I will be opening the top of the bag every now & then to examine the progress & remoisting the bag. Some recommend covering the bag with alumunium foil to keep it moist.
Here's a video from You tube if you are interested.