Can't connect to postgresql database (have read other post )

Hello Everyone,

I cannot connect to the database, but don't know where to begin to diagnose the problem.
How do I start to define the issue. My system specs are in my signature.
Thank you in advance for any help anyone can give.

I have read other post, but often they figure it out, but don't list the step by step of how it was done.

Kind regards,
Robert

Little update from above. I checked and postgreSQL hasn't started. It didn't auto load when the mac started. How do I rectify this?