How to see nodes for a different custom usergroup

[ScrapDog]

I need to know how to give only acces to a different thing else like : $xf.visitor.is_admin

I need to give acces in the navigation bar to a group called "artistic", so what is the syntax for giving access to a navigationbutton and is only visible if your member of the group "artistic" ?

Sincerely,

ScrapDog