Where to learn PostgreSQL for free?

Hi,

I need to learn PostgreSQL and some other new skills, worried about finding a new job sort of.

Budget wise, I don't have the means to do so, especially financially.

Does anyone know of any site that is offering free resources to learn PostgreSQL, install, scripting, backup and recovery.

I had AWS Free Tier before but that was hacked so I was a bit worried about going back. Also, I will want to do some install exercise, not sure if that is something that is possible with AWS as they are pre-build, isn't it?

I am sure performance tuning will take a lifetime to learn.

Regards,

Edwin