How do you get the components to go in the specific column as opposed to just being added to a new row?

Immediately before clicking on the '+' sign to add to the layout panel a component from the Content pane, I select the element into which I want the component to be added. I make that selection either
(a) by double-clicking on it in the Inspector panel (which takes one to the Design panel for the element selected) and then going back to the Component panel, or
(b) by selecting it with the mouse in the main layout panel.

If, as I suspect, the above procedure is already known but doesn't seem to work for placing certain components, I guess that those particular components are themselves rows or columns with content, and therefore cannot be fitted within other rows or columns.

Frank