What do you mean by "break it down to different parts as the old one" and "seperate these parts from the entity"?
Well, it sounds like you want to explode the view of the fastener stack like the other screws in that screen capture you posted.
to do that, edit the exploded view.
You should read up on exploded views and do the tutorials that come with Solidworks. Exploded views are taught in the 'Advanced Drawings' tutorial. Tutorials are accessed from the 'Help' menu.
Thanks a lot gentlemen! Sorry, Paul, I did not explain clearly enough, but I will look into John's advice.