In Designer Pro 11 there is a Google search widget under the design gallery in the other widget folder. Not sure if this widget is in WD 11 if not you can also go to Google's site https://cse.google.com/cse/ to sign up and get the code to add a search function for your site.

Here is a website that has code for Google, Bing or even Yahoo to setup a search box:
http://www.developerdrive.com/2012/0...-your-website/
You should be able to add this code to a place holder and have either one of these for your site.

Hope this helps

Ray