A sidebar is a small section that is positioned next to long articles. Sidebar holds information about your website and about your articles. In this theme, you can find sidebar in the middle news area.
Click on Dashboard> Appearance> Customize> Widgets
Click on Sidebar
Click on Add a widget to add widgets. You can click on the existing widgets to change the title name and other properties of the widgets. You can also delete the widgets and rearrange the order of the widgets.