I am beginner just started today i got problem with arm its sharp when i move the right arm

I am guessing you cut the arm along the side of the body? Basically the arm should overlap the. body,and I normally put a semi-circle on the end of the arm so you can rotate it around and its curved (no sharp bits). I would also suggest learning how to take screenshots of the screen using software (using Google - lots of articles). You are welcome to ask lots of questions, but a common one is for a copy of the rigging hierarchy and taking a photo like that will come out too blurry I think.