About applying any sort of effect in camera: DON'T DO IT !
Imagine if you just happen to take the best photo you ever took - surely you would want to have it in all its glory, right? People so often regret having only a b&w (or other effect) photo, and ask how to turn it back into colour, which of course is impossible to do.
Always set your camera to biggest size, best quality (and to color).
That way, you start with the best possible photo as your original.
Then you make a copy and edit it to your heart's content.
You have much better control over any editing on your computer, even something as simple as b&w will look MUCH better when it was processed properly instead of in camera.
You can do all sorts of things to it PLUS you get to keep your original.
If you're determined to ignore this advice and do it in camera, anyway, READ THE MANUAL and/or the manufacturer's website and/or your camera's menu.