i've been praticing to throw the circle change the way Mr. ellis told me to by throwing the 'Ok" at the target and this made my shoulder really sore but it doesn't hurt. Will it cause an injury? or is it just becasue i am not use to the way i throw it yet?
Most likely the soreness is due to your using muscles that you haven't used before.
However, you could have a problem with your mechanics.
Do you have a video of yourself throwing?