Why cant you pull back your forskin?

Probably because you have not begun to stretch it yet. Normally young boys have a tendency to play with and manipulate the foreskin because it feels good. However if you find that your foreskin is tight around the glans you will need to take the situation in hand so to speak. and put you fore skin through some stretching exercises. This is literally what it sounds like. Stretch your foreskin as much as you can without hurting your self and hold it that way for as long as you can. Doing it under a hot shower or in a warm bath regularly fro a couple of weeks should have it moving backwards and forwards properly in no time. Remember the moment you are able to retract your foreskin you are also committed to washing under it as from that time on bacteria can get under there,