it takes time, im 16 and been using tampons for three years, once you get it right, you can never forget it, if it hurts when you do insert it, its not up far enough, try using applicator tampons as they insert it for you and means its easier to find the 'position' of where the tampon should be
you cannot insert tampoon it doesent mean your body is abnormal. may be you dont know how to use it. take some body help to get a demonstration done how to use tampoon this might help.