Hi there i am a very newbie

I am trying to draw a zigarat (multilevel pyramid) but am falling at the first hurdle.

How do i centre two squares? i cant even figure out how to do it in 2d

If anyone could show me via a video that'd be amazing as i've been googling and following tutorials and cant fathom it.

I literally just want an easy way of making ever smaller squares perfectly centred within eachother.

Please can anyone help?