padding

I have having an issue removing the padding from the regions within in the Acquia Prosper theme. I am fairly new to Drupal and Acquia Prosper, so I hope my explanations are sufficient.

Firstly, if you look at the first attached file (help1.png), I cannot removing the spacing at the sides of the shopping cart, that is contained within the "sidebar-last" region. I have set the padding in the the local.css file to zero but no luck.