Snapping to Grid - Ship Builder help

I’m starting a project and I can’t seem to figure out how to make a custom grid, I’ve created the frame asset and a placeholder module that’s supposed to snap to it but I can’t figure out how to do what I’m trying to. It’s supposed to be a 3 by 10 collection of those frames I can put the modules in to. Does anyone have a good place to start?

I am a complete novice, I watched a Udemy course but I can’t seem to get started with this… I appreciate the help.

Top-right of the viewport, make sure the waffle button is orange; default snap distance is 10 units (0.1m).