How to reach the module's control pannel

Hi,

First, thanx for this beautifull theme. That's the one I've choosed for http://www.locfacile.net, a service dedicated to personnal car rent in France.

I'd like to modufy the columns width as this possibility is mentionned on the theme presentation page http://www.alldrupalthemes.com/web-application.html ; and illustrated in the second picture. But I can't even get this page under the administration>theme>options pannel.

So, how can I reach this page ?

Many, many thanks !

Romain
France