Need help coding different footstep sounds on different surfaces - Beginner`

I’m using the first person character controller. The way i’m trying to do it is with box colliders and tags. So, i have my stone floors tagged with “stone” and my grass surfaces tagged with “grass”. I have a very, very basic understanding of coding. I don’t even know how to get started, really. A few people have suggested raycasting straight down, but I’m not sure how to do that at all. My main problem when people send me code is I’m not sure what to replace with my own. Thank so much ahead of time if anyone is able to help me! I’m using C#.

Check this one:
https://forum.unity3d.com/threads/detecting-terrain-texture-at-position.94723/
It’s for terrain, and give us your code.