Hello,
I am new to blender. I switched from Cinema 4D and that is a nightmare for me. I am getting used to blender workflow with every day but I can’t understand one thing.
For example when I was making a house in Cinema 4D and I modeled a window. I added it to null group called window and than I duplicate it and put in place. Than I could create one big group for all of the windows to move them together or select one window.
How to do this in blender is a black magic for me 
Groups are a little weird in Blender. Myself, I’d create your window in a layer by it’s self, at the centre of the scene, then select all the bits of it, and press Ctrl+G (group).
Now, go back to your main scene, create an Empty, and in the object settings > Duplication, Group. Your Window will now be attatched to the Empty.
You can now duplicate your empty a bunch of times.
You could then group your empties that have windows attached.
Groups is blender kind of suck, but in 2.8 the developers substituted it with a new collection system which makes alot more sense and is more like the system in cinema 4d…
a.) There is no Grouping in C4D per se, it is simply Object Management - constituting a hierarchy, structuring Parent / Child relationship.
b.) You’re not familiar with Blender, so how can you possibly predict what to do & achieve your goal?
Do the same as you did in C4D (construct a hierarchy):
Learn about Good Parenting in Blender
Groups in Blender are more in line with the way Max Groups are.
Sort of an abstraction layer that comes in handy for/when duplicating, instancing or proxying.
They don’t suck, but human ignorance & laziness to not educate (enlighten) self sure does!
Black magic 
Ad a.) Yes you are righr there is no grouping in C4D
Ad b.) I cannot predict the outcome of my actions in blender but I am trying different things to achieve my goals. If it fails and I am stuck I am looking for the answer by asking someone with more experience.
Thanks for the link. I will check it out. I am just saying it was more intuitive for me in C4D but I am not telling it was better. I just need to understand how to do it in blender.
I never said they suck. They feel like black magic for me now and I am not lazy or ignorant. In my opinion asking questions is part of education.
Thanks burnin.
Yeah, was not meant specifically to you (this one is, as you may notice) but to all who find themselves struggling with kind-alike thoughts while reading this texts… including me, as i might forget it all one day.
Keep the spirit high