a) Click on Options on the left side of the main menu.
b) Then click on Options again.
c) Click on Head.
d) The menu item "HTML" is automatically selected.
On the right side you can now enter your code:
Note: Open a second browser and display your website there in visitor view (logged out). In admin mode the code in the header is not active.
This feature is only available in the purchased versions and hidden in the free versions.