All of these sections are known as widgets and are accessible via Appearance > Widgets.
It will look like this:
Sidebar
This appears on a blog category screen.
Post Sidebar
This appears on a single individual article.
Home Sidebar
This appears if you've chosen a homepage template which includes a sidebar.
Pages Sidebar
This appears on a page so long as 'Full width' is not selected via the Template dropdown.
Shop Sidebar
This appears if you have installed WooCommerce.
Footer
This is the main footer section.
Instagram Footer
This is used is you have set up the Instagram Widget.