Is it possible to have an external link with the main menu?
In the Content > Metadata > URL, it is already set to http://localhost/myweb/index.php/.../ so I cannot find out how to create an external link, let's say http://www.google.com
This is easy once you know how - create a new page from the dropdown above the pagetree in the CMS. But rather than selecting "New Page" choose "New Redirector Page". This will allow you to enter the link address.