It is now in the side navigation - turn editing on and open the sidebar (on left).
I am using v3.6, and I am not seeing it.
If I switch to the boost theme, and I turn block editing on, I get an "add block" box in the navigation area on the left side. With the Fordson theme, that is missing.
While in edit mode, you should see "Course Blocks" close to the top right margin. Click on "Course Blocks" and you will see "Add a block."
