Adding an external link to my navbar

Hey peeps, I recently installed wordpress on my main domain http://www.lucianvision.com.
I’m presently using the Azul them, and need abit of help.

Basically, in my navbar, it shows my pages…. “home” and “about”

I want to know how to add some more links into my navbar, that are not pages… example, I want to add say… “forum” in my navbar, linking it to “http://forum.lucianvision.com”

Any help is appreciated. Thanks