You can add a link to an external site from your main nav bar. This feature is also useful in adding a link to an uploaded .pdf document, or a different section of your site directly into your top or left-navigation.
1.) Select "add a new subsection" under the menu nav option would like the external link to appear under.
2.) Add the name you would like to show up in the nav menu to the field at the top. Copy and paste the link you would like to direct users to in the URL field, and click add new or hit the return key. Note: The link will initially be turned off, and you will need to toggle the red button to turn it on and make it show up in the nav bar.
3.) You should have the new link in your nav menu.