I want to add a popup box to my site like this one here: www.textinchurch.com
I've created the box through MailChimp so it links to my subscriber list, but I can't seem to find a way to add the HTML to a GoDaddy theme. I've tried adding it to the site code in header and body and neither work. I've also tried adding it as an HTML box on the site, but that doesn't allow it to pop up. It just makes it into a permanent box on the background of my page. Any suggestions?