You have the ability to redirect your pages to another site. You may want to do this if you need to add an external link inside of your Subpage Box. 

1. Go to the page you want to redirect. 
2. Click on Page Properties. 
3. Click on Advanced. 
4. Type in the full website address in the URL box at the top. 
5. Click on Save. 

Please note that the redirect will not work while you are logged in as the administrator of the website. You will need to log out of the site to test the link.