Changing Sidebar width and Content Area width.

I’ve searched the forum in great detail, and altered the php files and css files in my theme directory. Here is what I’ve been able to figure out so far.

-how to make the content area bigger
-how to make the menu thinner

I cannot get the menu to move with the scaling of the content area. They overlap when I increase the width of the content area. How do you get the menu to move with the size of the content area?