I have started yesterday…
and continued but I have no experience with Zbrush I have only been sculpting from normal Zsphere but I want to no how to use it properly eg. I don’t how to sculpt the Alien Helmet quickly.
ZSpheres are just a starting point. Don’t try to use them to actually detail the model; instead, just rough out the shape that you want and move on.
To move on, use either Adaptive or Unified skinning. Instructions for how to do this are in the video tutorials about ZSpheres at the ZClassroom. See my signature.
Once skinned (creating your base mesh), you can then sculpt that mesh however you’d like using the standard sculpting method.
If the helmet is supposed to fit another model, then instead of ZSpheres you could just mask the portions of the head where you want the helmet to be and use Mesh Extract. This immediately creates a form-fitting mesh as a new SubTool. Unmask that new tool and jump right into sculpting.
the only thing is that I did watch the videos it is just that the one with Zspheres was a bit difficult to understand 
but thnx a lot