Blog — How to add a sidebar?

Navigate to Appearance > Customize > Blog > Blog Posts Archive and Enable the Blog with Sidebar option.

Please note that the sidebar is not available with all layouts options for the blog.

How to add widgets to Blog sidebar?

You have a a list of Widgets you can choose from when it comes to making the sidebar functional, for this go to Appearance > Widgets. Choose the ones you need and add them to the Sidebar: