See no options to import IMGs into any type gallery, Seriously tried everything.

Problem #1) No matter what I try, I cannot get my images from the Media Library and into any new gallery of any type. I’ve tried everything I could imagine. Tried importing directly, tried dragging and dropping.
Problem #2) I have not found a word on the topic in the documents or in any forum.
This means importing images into any gallery, masonry or portfolio, must be intuitive and simple or there would be other forums about it. This also means I must be missing something in my docs and my dashboard… or that I have yet another glitch.

I’d be happy to be proven stupid on this one, but someone please help, I can’t spend another hour trying the same things over and over and over..

I have the images in Media Library, I have both a masonry grid and a porfolio grid I’ve been trying to get them into – both inside a color section and on its own. Nothing works and I see no instructions.

To recap what I need: The steps to import images into a gallery and link respective images to their filter category.