Making a link from a menu item to a URL is easy. But there is no built-in support for making that external URL open in a new window.

So we will employ a small bit of javascript code that will perform this function for us. Here are the steps:

1. Go to your page you want to use for the link and click into the page settings.
2. Expand the Advanced Settings
3. Expand Other Settings, if necessary.
4. Select URL for the link type
5. In the URL box that appears, insert the following as the URL
   
   javascript:void(window.open('http://www.google.com'))
    
6. Change the link to Google in that code to your desired URL
7. Update your settings and try clicking the menu

 Note: After you perform these steps, if you need to edit the page settings again for any reason, you will have to go to Pages on the Admin menu. Once there, select the page name and then the little pencil on the right.