How to adjust the body and sidebar width

I’d like to make the body/post area a little wider and the sidebar thinner. I’ve tried adjusting under the content section

Then I tried adjusting under theme and layout no matter what I change the size stays the same
my site is http://www.valleyofthekings3dfilms.com if anyone can help

Also is there a way to change the tan color of the sidebar area to black?

I appreciate any help i can get on this