Blender 2.8 collections and objects

I am working out how to separately render objects in view of compositing them . On the snap shot attached one can see that I have tried to create 4 collections that should contain each of my objects so that later I can render them separately and composit them.
The issue is if I use Ctrl M, it opens the window with option to create a collection for the selected object. Which I did, but instead of having my object in the selected collection, it gets out of all the collections?? If I try to grab it and drag it into a collection… no result!
Can somebody explain me how does the collection model works? Also what is the render layer above the collection? Why to name it layer and not a collection like the rest? This is really confusing… unless I missed something in the few video on that subject…

I think what’s confusing you the most is having the “scenes” display in the outliner, which shows the hierearchies of whats in your scene categorized by collections, objects and viewlayers. Thus, you won’t see there which objects belong to which collection or which collections are linked to which view layers. I think you’ll understand everything better if you switch to the “view layer” view in the outliner.
I hope it helps, english is not my first language so I hope i’m being acceptably clear.

thank you for that tip… effectively layer view is more efficient… Thanks again… and BTW your english is very good…