Menu link to open in a new tab/window

I recently bought a theme which it turns out uses the Genesis framework … and it’s proving a nightmare to work with!!
I have set various menu links to pages but I have one in particular which I need to have open in a new tab/window … but I can’t see how to achieve this in the current structure as there is no option i the menu settings.
I installed your plugin … but as I have little or no experience of programming I can’t see how to use the plugin the alter the behaviour of the menu link to the weather page.

Defo not a job for a beginner !!! Any assistance would be most helpful. Many thanks

The page I need help with: [log in to see the link]