Help with Grapher

I'd like to use the Grapher app (in Utilities), but not being very familiar with mathematical terminology and how to determine which function I should use to achieve my ends, I sought to consult "Help". On my computer at least, it does not appear to exist. A Help pane opened, and displayed a Contents page that linked to an Index page but any attempt to go further was met with an error page, informing me that the page I sought did not exist.

Is this simply a fault with my installation or the program as deliverd by Apple?

If there is no Help available for this program - anywhere, would someone (more capable than I) care to assist me in learning how to use Grapher? It looks like an excellent program.