How do I modify each move to work for my body if the modifications aren’t shown? 

If the modifications are not shown then try to find an alternate exercise that you are comfortable doing that works the same body parts being worked in the routine, or that keeps your heart rate up. If you are not sure how to do this, just take a break and rest until the next move or march in place. Just keep moving. Also, you can watch my Exercise Modification videos available in my iOS app to learn how to do them.