You can add a sidebar to any page by going to the page settings. You can also add columns.
Step 1
Go to the Pages tab.
Step 2
Click on the Settings (gear) icon.
Step 3
Next to Content section, indicate whether you want to add a sidebar to this page.
Step 4
Click on Save to add the sidebar, or click on Cancel if you don't want to apply the changes.
⚠ Note: Sidebars can only be used with certain Designs.