the old story....
go to wb-options -> advanced settings and check, that the point "Section Blocks" is activated - if not, set it to activate and save your settings
for the next step it give's many possible way's
i use the sidebar not on all pages, my solution is:
1. on the first page, where you planed to use the sidebar, go to Managed sections (top right corner in the first section of the backend/ page
2. add a new section to the first, type is, what you need in the sidebar (mostly: wysiwyg)
2. now you have a table with a list with your used sections on this page. every section has a select-field with the option (in bagslyd) Main or Sidebar. Set the new section to Sidebar and save the changes
4. put some content into this section and save this - now you can see this content in your sidebar
i use the sidebar on ca 30-40% with the same content (contact data etc), for this solution i need only one section in Block "Sidebar" to edit, for the other pages i use the droplet section-Picker with the ID from my first sidebar-Content and the pages without sidebar use the full-wide-screen
if you need the same content in the sidebar everywhere....
its also possible to build a "stand-alone"-page (invisible) with the sidebar-content and a sectionpicker-code directly in the index.php of the template
or the globalBlocks-snippet
if you need different content on every page in the sidebar....
see my points 1-4 and build new sections on every page