Theme comes with default sidebars. You can add widgets to the sidebar using Appearance > Widgets You will find your selected widget on the right side. Simply drag and drop widgets you want from the left side boxes into the sidebar box.
If you want to add your custom sidebar. Go to Theme Setting > Sidebar > Custom Sidebar Settings and sidebar name and click Save All Changes button.
Sidebar Colors and Styling
You can change sidebar font size, font family, font color and etc. Go to Theme Setting > Sidebar > Sidebar Font Settings and Theme Setting > Sidebar > Sidebar Content Colors Settings