I'm sorry, I don't understand what you're trying to do. The create menu link simply creates a internal Joomla menu link under the menutype "GroupJive".

as you can see in the picture 1 i can't create a menù of GJ

Of course not, GJ isn't a Joomla extension. As I've explained you need to use the "Create Menu" links from within GJs backend as seen next to the "Frontend URL".

in the picture 2 you can see what's appen if i pubblish the auto-created menù with the link on GJ section.. only a blank space

Blank space where? I don't know what I'm supposed to be looking for in this image.

in picture 3 you can see my GJ menù active & pubblic!

Right, but what does that have to do with image 2 or creating groups? I don't understand what your issue is. To create groups you need to navigate to GJs frontend, navigate to a category, then click the New Group link on the categories menu.

2. i will re post the image, in the red circle you will see the "phantom" position, the place are taken, but i can't see the menù!

I don't know what that has to do with GJ, sorry. You're not even on GJs frontend page or CBs for that matter. It looks like the Left module position or something similar for your Joomla template.

3. yes... but how i can navigate in GJ if i haven't a link/menù?????

You need to move it to a menu that has a module or create a module for the menutype GroupJive.