How To Plugin Page Option(s) Using Ajax?

Thanks, so I set up the example from https://codex.wordpress.org/AJAX_in_Plugins. The only thing I can’t see is where they are get wp_ajax_my_action where is the my_action part in the hook coming from? Their example worked and then I played with it and now it doesn’t and it appears it might be because of that weird hook name. I tried using http://codex.wordpress.org/Plugin_API/Action_Reference/wp_ajax_(action) to choose the name but still returning 0.

The client side is the same except I change whatever to option_name and the action is set to calendar_schedule_options.

add_action('wp_ajax_calendar_schedule_options', 'ajax_get_calendar_schedule_options');
function ajax_get_calendar_schedule_options()
{
	global $wpdb;
	$tmp = get_option('my_plugin_options');
	$option = $_POST['option_name'];
	$option = $tmp[$option];
	echo "$option";
	die(); // Required to return a proper result
}