Sidebar not showing up
2 step: Go to Appearance > Widgets section and already created sidebar from step no. 1 will be waiting for you. Just put right widgets into sidebar.
3 step: If you want to select this sidebar for page, then please go to Pages section and edit page for which you want sidebar. Under Content Builder section you have 2 values:
3.1) Layout (choose if you want sidebar on left or right side)
3.2) Sidebar (select already created sidebar for page)
Comments
are you sure widgets exist in the sidebar? Because sidebar may be empty.