Links In Navigation

We can now add navigation links to outside URLs. 

Below are the new instructions. 

If you don't see the new link option you should see it soon. 

When you add a link you can search for what you want to link to: as you start to type the link you will see suggestions:

THIS SITE that gives links to pages of current site andALL RESULTS that gives links to Other Google Sites pages you can editItems in Google Drive like Google Docs, Sheets, Slides and files (e.g. PDFs) you have stored in Google Drive

You can select to open the link in the same or a new tab.

More details in Steegle's instructions.

Add a link in your site menu

You can also make navigation links to targets within a page.
(Even though Google doesn't offer this method, it seems to work for me).