Sidebar
Berg Theme has 4 sidebars and widgetized ares for them, one for post in the Classic Blog Template and one for all the Pages with Default Template and one for Post with Post Template Image on Top. You can choose its position: right, left or none. Additionally you have one for the sidbar created with Visual Compser.
You need to populate them with widgets of your choice under Appearance > Widgets. Simply drag and drop your widgets in required order.