[Theme: Twenty Eleven] Remove Pages Links from Header

I’ve searched high and low on how to remove the pages links from the header.
I have installed “Twenty Eleven Three Menus” and been able to create a footer menu that works, and lists the pages, but whenever I create new pages the links automatically get put on the Header.
I’m a Newbie to all this; I gather that I should not edit the theme directly, but should do it in a child theme. However, I need step-by-step instructions on how to do that, not just – for example – “create a directory in your file manager section of the c-panel”. I tried doing that by creating a twenty eleven-child folder inbut when I tried to copy the style.css I created in Notepad, it just wouldn’t save. I suspect I was doing something wrong. A post I read said, “Drop the file in the folder,’ but when I did that nothing happened!
So besides my need to be taken step by step through creating a child theme, I need to know exactly what code to delete from the style sheet afterwards. Many thanks in advance. ersl/Rodney