This exercise not only focuses on upper body strength, but it is very demanding on your core muscles. You will be focusing on strengthening your shoulder muscles along with your biceps, triceps, and core muscles. Keeping your core nice and tight will allow you to stay stable during the exercise and keep your hips from dropping too low.
On a Woodway treadmill, you can put it into "dynamic mode" where the belt of the treadmill moves only by using your body weight. However, you could also use a regular treadmill and put it on a very slow speed. In order to put the treadmill into dynamic mode on a woodway treadmill, you push the + and the – speed buttons simultaneously, which is on the right hand side, until the treadmill beeps and says "dynamic mode." You then want to get into a plank position with your feet on the floor and your hands on the treadmill. Make sure your shoulders and hands are lined up together. You then want to slowly push the treadmill forward with your hands and make the movements small. If this exercise is too challenging, you can do "1 arm pushes" which is when you put one hand on the side of the treadmill (on the grip) and push the treadmill forward with 1 hand and then switch to the other side. If that is too challenging, you can do this exercise on your knees.
Try 3x10 of this exercise and see how you do. Start slow and work your way up. If you haven't tried a woodway treadmill, I highly recommend it! It feels like you are running on clouds and you can do a lot of great body weight exercises on it as well.