Easiest way to create a simple popup?

Just trying to make a simple popup. It will just be an image that when clicked takes you to a URL.
You should be able to click an x or something to close.

I would have thought there would be a simple wordpress plugin or script..but none of them seem to really work that I've found. They are all geared towards capturing emails and form submissions.

try this, he has some good wordpress plugins and they are free
http://www.gopiplus.com/work/2013/08/08/popup-with-fancybox-wordpress-plugin/