How to change a single tilemap by coding?

Hello everyone

These days I'm working on a 2D project and I found no way to change a single tilemap grid by code, so I'm wondering if someone knew how to do it.

Like you see in the picture, for example, if I want to change the ground "a" to grass on the right side when something happened, how can I code to reach this?

The problem is that I don't know how to select the grid specified, when I click, it will be selected the whole tilemap object in the hierarchy.

 

From the documentation:

https://docs.unity3d.com/ScriptReference/Tilemaps.Tilemap.SetTile.html

 

Thanks a lot!!!