Issue after adding Mailchimp form code

First, I’m a newbie and have been happily making changes around my website with some success.

Until now. (It was only a matter of time).

I wanted to add the MailChimp sign-up widget, which for whatever reason would not show up on my site no matter what I did. (Installed ok, just a no-show).

So I thought I would add the code to my home page. It worked. I have a sign up box. Unfortunately, everything else on that page has turned into a hot mess. The layout is totally messed up now, and so far my ideas on how to fix have not worked. Any ideas?

The site is http://www.greendoorvirtual.com