Twenty Thirteen is a new default theme of WordPress for 2013. The default style of Twenty Thirteen is without sidebars. But you can use a sidebar in Twenty Thirteen with the sticky sidebar feature of Standard Widget Extensions plugin if you like. I’ll explain how to do that.
1. Enabling Sidebar
Twenty Thirteen has two widget areas. One is for the footer and the other is for the sidebar. If you place widgets in ‘Secondary Widget Area’, a sidebar will appear automatically.
2. Theme Modification
Twenty Thirteen’s sidebar doesn’t have a proper ID to use. So you need to attach an ID to it by editing theme files.
In your sidebar.php, please insert an id for the sidebar as follows (diff format).
if ( is_active_sidebar( 'sidebar-2' ) ) : ?>