Containers are used the same way every other component is used, by clicking and dragging the component from the toolbar onto the page. Once you have dragged a Container component onto the page, you can see that it looks similar to a dropzone. What containers are used for is bumping the content of a page in slightly to a centered column. Any time you see a page that has a thinner column of content than the width of the browser, they are using a container.
Containers are great for adding a nice buffer and increasing the readability of your page.
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