Guys I have another question, I have to add a button inside an iframe and, when this button is clicked, automatically click another button (that is original inside the page). How can I do this? Can you please post me the full code? I don't know how to do and I didn't find anything.

This is the scheme-> when iframe is loaded button appear in a specific part of iframe.-> People click in this button and, automatically, another button (not added, but button that have the page) are clicked. Then the button added disappear.

Thanks