change row width on homepage only

I am trying to change the row width on the homepage only, the site is
here. Wanting the white box to align with the image (image is 900px). I went into the row settings but there is no box to change the width.

Hi Pauline,

Can you provide temp admin access, please. As, your image appears to be part of a three column layout with one column either side. If you remove those it should align the image with your content.