adding html code for others to copy from your site

Hi…I am triing to add a “grab a button” section on my site, I have a button, but can’t figure out how to add the html code…Here’s an example of what I am talking about.
http://freeprintablefun.org/ Scroll down a little bit and on the left you will see “Grab My Button!” and a little area where they have an html code a person can copy to put the button on there own site.

HOW do I get that little box to show my html code on my site????