How to make the banner slider align with the menu above it?

[rookiecoder]

I am using onebyone sliders. The width of the banner is stretched across the page. How to reduce the width and make it align with the menu above it? the new width of the banner should equal to the width of the menu header above it. Thanks for any tips.

[rookiecoder]

   margin-left: auto;
   margin-right: auto;

added these lines and voila!