Adventurous Free Theme: Change sidebar content area colour

Good morning I am trying to change the content area colour of the main sidebar but so far I've not been successful. I can change the page area colour, found the 'how to' in the forum, but as much as I try the sidebar content area remains white. I am using the Custom Sidebars plugin by WPMU Dev as I need different text in all my sidebars. I should add I'm almost a complete novice with WordPress. Thank you