Hi friktion321
If you haven’t done so already create a child_theme then you will need to copy over the header.pp and functions.php and edit them accordingly
Then – http://codex.wordpress.org/Function_Reference/register_nav_menus
Please try this then let me know the url and I will try and help you with the centering
i must be doing something wrong because every time i copy the functions.php to my child_theme i get
Fatal error: Cannot redeclare twentyfourteen_content_width() (previously declared in /home3/friktion/public_html/wp-content/themes/twentyfourteen-child/functions.php:128) in /home3/friktion/public_html/wp-content/themes/twentyfourteen/functions.php on line 131
and my page fails to load.
Do not copy over the functions.php as you’ll be duplicating the function calls and will always get those errors.
Create a new file in your child theme and name it functions.php – you’d then be able to create your own function calls prefixed with your child theme slug and adjust them to suit your needs.
I your case you only need register the new nav menu in functions.php, From there on you can add the call to it in header.php where you want it to appear followed by some CSS work in your child theme’s style.css
