To add your Google AdWords Conversion Tracking Code, navigate to Avada > Theme Options > Advanced > Code Fields (Tracking etc.), and insert the code in the Tracking Code field. Place the code inside of < script > tags. Below is an example code snippet added to the Theme Options. This will be added into the header template of the website and will affect your entire site.
If you want to insert the code in the content area of a specific page only, then, you can do it using the Code Block Element of the Fusion Builder. However, if you need the code inside the header area of a particular page, you will need to add and make use of a Child Theme to add the custom code.