Before we begin, I will be very frank and state that hair extension and replacement is an art. To master this or any other technique will take time and practice.
Adding extensions by pinch braiding is called braid fusion. Bulk hair is braided with the natural hair to hold it securely. Most of you may already know how to do this, but what you may not know is that there is a difference in pinch braiding for braids and pinch braiding for a loose hair look. For a loose hair look, a strand of silk or other beauty grade thread should be added along with the bulk hair, and this wrapped and then tied around all of the strands at the point that you stop braiding. This helps to blend the natural hair with the extension and to give it a more neat appearance.
Basic Braid Fusion Step-by-step