Generate random pattern of pressure plates

Hello everyone,

I’m working on a simple puzzle game with pressure plates: when you press the right pattern it unlock a door.
So I have 6 ‘‘Good plates’’ BP and 1 ‘‘Bad plates’’ BP, I’d like to set randomly the position of the 6 good plates on a 6*6 surface and fill the empty spots with the 30 bad plates at the start of the game.

Everything work for now except for the random generation, if anyone can explain me how he would do that, it will help a lot, because everything ^^

Thank you for the answer, it gave me an idea on how to setup it, I’ll try it ^^