Addressing your issue in general terms of front-end development and leaving aside the possibilities of the Google Web Design tool.
There are several ways to include your banner / rodrigo.html page, I say that the iframe attribute is not the best option for this case as it is very limited. I emphasize that iframe is not necessarily wrong, just that it is not good practice.
If you're developing with PHP, you can dynamically add your page as follows:
<?php include 'banner/rodrigo.html'; ?>
Practice inclusion with PHP this link.
If you are just developing the design itself, no dynamic content, you can use Javascript as follows:
Include the <script> tag in the <head> of your site, it will contain the information of the file to be included and the <div> that will be used.
<html>
<head>
<script src="jquery.js"></script>
<script>
$(function(){
$("#include").load("banner/rodrigo.html");
});
</script>
</head>
<body>
<div id="include"></div>
</body>
</html>
Read more about inclusion via Javascript in this topic.
* Since Google Web Design must include jquery, you will not need the tag that calls the library.
* Note that I'm not considering the contents of your banner/rodrigo.html file, your .css file, jquery conflicts, etc.
