The following KB articles relate to this topic:
"Sidebars" in the CMS refer to the tan column on the right or left side of the page which provide space to link to additional navigation. The sidebar is not a content class. Instead, you can add or remove a sidebar by opening a page and editing the Layout Settings in the Page Information.
In the responsive template, the width of the sidebar can be manipulated (also in the Layout Settings). The default width of the sidebar, when it is turned on, is 3 units. The sidebar for this page is located to the right of this text and appears as a tall, tan column.