Click on Appearance -> Widgets.

Here you can add and organize your widgets.
Drag and drop elements from the left to the Right Sidebar.

When editing a widget, always remember to click Save it before leaving the page.

Adding  Widgets to Overlay Sidebar

Go to Appearance -> Widgets.

Here you can add and organize your widgets.
Drag and drop elements from the left to the Off Canvas Sidebar.

When editing a widget, always remember to click Save before leaving the page.