If you use this header combination and you wish to center menu as well, please read further.
Select header type 2 with logo centered
Below css will align menu in center (use this ONLY if you don’t enable the user menu in header). By default menu is on the left and user menu is on the right. Add this css in child theme (see theme pack for child theme zip):
Help for how to add custom css in theme: http://help.wpresidence.net/article/how-to-add-custom-css/