In the page header set the Page style option to Full width.
If you want to customise the colour of the areas to the left and right of the slideshow container then you’ll need to borrow the following CSS from the skin 3 stylesheet:
#SubHeader.fullWidth {
background: #99271F;
background: -webkit-gradient(linear, left top, left bottom, from(#99271F), to(#73140F));
background: -moz-linear-gradient(top, #99271F, #73140F);
background: linear-gradient(#99271F, #73140F);
-pie-background: linear-gradient(#99271F, #73140F); }
Put it in your Custom CSS box and adjust the style to your requirements.