Please help! How to use PHP snippet for html?

Try to close the PHP tag with ?> where you want to put in HTML and open PHP when ready with <?php

You’re confusing PHP and Javascript I think. For stuff like this, I would recommend you test this out on a static page first, then try it on a stand-alone PHP page, and only then when everything was working should you try to move it into WordPress. If your code doesn’t work in the previous scenarios, there’s no way it will magically start working once it’s inside WordPress.