Note: You can add and configure sidebars here using following steps. But, to add tools to the sidebar you should go to Appearance > Widgets.

Please follow the following steps to configure Sidebar settings:

• Go to Appearance> Customize> Sidebar Settings
• Click on  Add New sidebar button
• Give a name to the sidebar
• Click on Publish button

You can also see the new sidebar in Appearance> Widgets.  You need to add a widget to the sidebar save button to configure the newly created sidebar.

Configure Sidebar:

• Go to Appearance> Customize> General Settings > Sidebar Settings
• Select Sidebars for various Pages, like Blog Page, Single Page, Single Post, etc. Particular pages will only be displayed under the sidebar
• Click on Publish