The only thing to do will be to set your new menu as the main menu for your site:

In the Theme Locations box simply select your new menu as the Primary Navigation for the site. Click Save and you're away! Note: Some themes have multiple places for menus in the theme. There will be more options here if that's the case.

And here's what it looks like:

Lovely.

There is one thing you will need to watch out for though. Any pages you add from now on to the site will need to be added to the menu manually. You can check the Automatically Add New Top Level Pages box but that would basically put the menu back to what it was. Best to spend the extra 30 seconds (if necessary) keeping your menu looking beautiful.