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
