In the HTML Source Editor window, add your HTML custom code. For example, the following HTML custom code can be used to embed a YouTube solar car video feed using a “solar car” tag (You Tube's Embed Code).
<iframe height="350" width="265" frameBorder="0" src="http://www.youtube.com/videos_list?tag=solar car" marginHeight="0" marginWidth="0" name="videos_list" id="videos_list"></iframe>