These exercises are just what they are called, retracting or bringing the head back.
Standing or sitting up straight, look straight ahead and allow yourself to completely relax. Move your head slowly and steadily backward until it is pulled back as far as you can go. Be sure not to tilt your head up or down but glide it straight back. I find doing this in front of a mirror and using one of your index fingers on your chin will help guide you.
Imagining a track your head is sliding on also helps. Once you bring the head back, hold for a 3 to 5 count and relax. Repeat for only 5 repetitions your first time performing them. Each day do another rep or two until you have worked up to 20 repetitions. Then, move on to using resistance below.
Perform this same exercise but with your hands holding gentle pressure against your head in the back. This creates some resistance making your muscles work a little harder. Like you are doing crunches, place both hands behind your head; perform the exercise above only with a little resistance of your hands. Only do this exercise once you are comfortable without the resistance. Also, if still in acute painDo Not do this yet; wait until you have gotten pain to subside. You can also do this one standing against a wall or lying down flat on the bed or even with a towel or elastic band for resistance.