Sometimes you need to add some blocks to all webpages. You can do that by configuring a Site template in the Site preferences section.
How to do that
For example, let's create two pages: one with a footer and the other one with a header. These pages will be used as areas when configuring the site template.
Then click Settings > Site preferences > More > Site Template > select a site template > select pages that will be used as areas.
Save changes. These areas will be added to all the other pages.
Configure a page template
You can configure a template for a separate page that will be different from a site template. Click Settings > Page preferences > More > click Apply to this page in Page Template section > select a template.
You can edit selected areas for each page. These changes will be applied to the selected page only.