sidebar
To Add an Sidebar or Widgets Search Attributes, first click on the pencil icon of Search Block

And then from the pop-up modal select the Widgets and click the add button.

The default Sidebar will look slimier to the below snap

To Add widgets to the sidebar first you have go to the sidebar Panel by clicking on the pencil icon. In the sidebar Panel you will find the settings tab.

From the select box select your sidebar name and click on the yellow save button.
After you save it the widgets will appear to that sidebar block.
