Adding a widget to your site takes just a few clicks. Set some options on the plugin settings page. Then go to your post edit page and pick up one of flight search widgets from
Thats it, the widget is ready to go. You can change some styles and set another custom parameters or just use it as is. Plugin will work fine both ways.
Since this plugin is free, the better way to know it is to use by your self.
Here are some articles to help if you still have questions.