To call an API from WordPress, you need a WordPress site and a RapidAPI account. Get an API key for the API, create a plugin to add a widget to your WordPress site, customize the plugin with your API key and specific information to display in the widget, and use the WordPress Admin Area to place the widget on your site where you want it within your theme. You can then use this plugin to integrate an external API into your WordPress site, such as displaying air quality data from a third-party service like ClimaCell Weather API. To do this, you need to replace the Xs in the code with your RapidAPI key and customize the widget to display the specific information you want to show. You can also choose different types of data or endpoints to retrieve from the API. Once you're happy with what the widget will display, activate the plugin and place it on your site using the WordPress Admin Area.