If you’re shooting digital I always recommend shooting in color and than changing to black and white in post. (that way you can always revert to color) If you shoot digital black and white there is no going back to color later.
However if you really want to shoot black and white in-camera you can try this. Go to your settings menu, you can choose an ambience setting from Vivid, Soft, Warm, Intense, Cool, Brighter, Darker to Monochrome. Choose Monochrome.
I think that’s how you get there if memory serves me correctly.
The main thing here is that I want you to see the before and after with and without this filter. Especially the sky and clouds.
No worries if you don’t get a chance to do this, the main thing here is to learn that filters are useful and that to achieve certain looks you need to use filters.