In Autodesk Fusion 360, right click on your model in the browser and press Share public link. You will be shown a link that could look something like this:

Go to that url in your browser, and it will redirect to a longer url, like this:

Copy that url, then paste it into this below snippet where it says URL HERE. This is the HTML iframe code that will embed this into your page:

<iframe src="URL HERE?mode=embed" allowfullscreen="true" 
webkitallowfullscreen="true" mozallowfullscreen="true" 
width="640" height="480" frameborder="0"></iframe>

Now we can test this: