child theme problems when moving menu below header

I am new to WP but I am following instructions for moving the menu under the header in theme Twenty Twelve.
In my host directory I created a -child theme folder, added new file with style.css and changed name and template to child theme.
Then I copied header.php from parent theme into new folder for child theme,
I then went back to WP dashboard and Activated child them in the Appearance/Themes area. I edited the code, moved nav bar to just before /header code.
A default header appeared and no menu/nav bar. I did some adjusting and now the header is there, three times on top of each other and on top of the menu/nav bar

Please help!