Changing sidebar size

Hi
I have just posted a support request here http://drupal.org/node/633508 regarding changing sidebar sizes. I would appreciate any help. I would like to increase the size of the right sidebard & correspondingly reduce the main content area size. I might also want to adjust the spaces between the main content area & the sidebars.
I have funny enough failed to see which style & style elements should be changed. The elements in the styles I tried made n difference.
I am using the "s12" dark skin.
Thanks in advance