mechanical constraint

Hello, As some of you may know, I am new to the idea of drawing mechanical instances. I have been following along in videos and learning Alibre Atom3D (my current subscription) by way of tutorials recently to learn more. So, in the bolt video, https://www.alibre.com/atom3d-training/ , I see...

I've looked at the videos for the new V21 mechanical constraints, but unlike the video for the standard constraints, they only show the result of applying the constraint. They don't show what geometry to constrain. In the screw shown below, what geometry do I pick for the constraint? I've...