How to make all screen black?

[summit]

Hello guys, I am working on a new project. I want to be all screen black. You can't see anything. And I'm going to show messages on screen. I will tell the story like that. I know how to show messages but I don't know how to make all screen black. So my messages look better with all screen black.

FadeOut(0); //This will fade the screen out instantly.

FadeIn(5); //This will fade the screen back in over 5 seconds.

Oh thanks, I thinked FadeOut and FadeIn works for another thing.

And there is one more question, I want to make my message stay on the screen like 30 seconds, how can I make it stay 30 sec with codes?