To start, make sure plugins are activated:
To clarify, you will need the two plugins from the screenshot above.
Elementor – Header, Footer & Blocks plugin works with all themes. Few of the themes have inbuilt support for this plugin while for a few you would need to choose compatibility method.
In case after activating the plugin, you see a notice –
Your current theme is not supported by Elementor – Header, Footer & Blocks plugin, click here to check available compatibility methods.
Navigate to Appearance > Header Footer Builder > Theme Support. Select a method to add theme support. In case these methods do not work, contact your theme author and request them to add support for the plugin.