Space Age is keeping me very busy

Great expansion!!!
I saw Nilaus making a ghost turrent with ammo in one of his videos.
But I fail to do it

Can someone help me and please explain what key I need to press?
How can I open the "set ghost cursor menu" ?
And how do you load ammo in a ghost build turret?
Here is the video: https://www.youtube.com/watch?v=n3yTCmzb0xE&t=75s
Thank you
