Sidebar Color

There are many tools available for this kind of CSS work, for example:
– Firefox with Firebug add-on: Help info on Firebug https://getfirebug.com/faq/
– Newer IE/Chrome, etc., have similar tools
– Alternately, try a dedicated CSS resource such as https://www.css-discuss.org/
– Also, consider creating a child theme otherwise all your customization will be overwritten when you next update your theme. Alternately, use Custom CSS Manager plugin: https://www.ads-software.com/plugins/custom-css-manager-plugin/

Thank you, but How do i access these tools?

https://codex.www.ads-software.com/Forum_Welcome#Include_as_Much_Information_as_Possible

to help with formatting questions, forum volunteers generally need a link to the site to be able to investigate the issue.

if you are using this theme https://en-ca.www.ads-software.com/themes/magnus/, you could better ask in https://www.ads-software.com/support/theme/magnus

somebody there might be more likely to be able to help without seeing your site (?)