You can open the help from the program menu (the item is called "Introductory help").
I just checked and the automatic opening this help at the program startup has some problems (specifically, the checkbox "Don't show again" is always off, even when the help isn't automatically started). I've modified the behavior slighly... anyway, to enable the automatic opening of this help, open the help from the menu and check the box "Don't show again"
- it will show again.