Trying to show how many lights are on

Is there anyone how can give me a step by step instruction on how to do this

I’m new to HA after transferring from sharp tools

I sort of understand the process, but am getting confused when you say add to yaml config etc, I have the editor but don’t know where to input it etc.

Appologies of this is “jannet and John”

Finding the whole thing rather confusing.

I think If I had a step by step instruction once I’d followed that I’d be able to do a bit more…