First you have to download "bootstrap.min.css", "bootstrap-theme.min.css" "jquery_min_1_10_1", and include css files in Style Sheets and JS file in UI Script.

Then create new UI Page and copy this code :

<!-- Latest compiled and minified CSS bootstrap.min.css-->

<!--The number here is sys id stylesheet-->

<!-- Optional theme bootstrap-theme.min-->

<!-- Latest compiled and minified JavaScript bootstrap.min 3.2.0 -->

Here in this example Class span has been replaced in this version 3.2.0 by col-xx-number , xx can be lg,md,sm or xs and number between 1 to 12.