You can move the default Genesis primary menu into the header of your page quite easily by adding it via a header widget as a custom menu.
By default the primary menu displays as a full width menu after the header
To change this and move it into the header, go to Appearance > Menus in WordPress dashboard select your main menu and ensure the Primary or Secondary locations are not ticked.
Adding in Custom Menu
Go to Appearance >Widgets and drag a Custom Menu widget into Header Right and the select your menu from the drop down and save.
Add in some CSS styling using the .genesis-nav-menu class