The best way to make the modules stick is to build something. These five projects take you from schema design through installing and configuring PostgreSQL, query tuning with indexes, automated backups and restores, and finally streaming replication.
Each one is a code-along video, so you can pause, type it out yourself and adapt it to your own ideas. Pick the project that matches the module you've just finished and come back for the rest.
Plan a database from requirements: draw an ER diagram, normalize the tables and turn the design into SQL. Pairs with Modules 01 and 02.
Install PostgreSQL on Ubuntu, edit postgresql.conf and pg_hba.conf, and allow remote connections from pgAdmin. Pairs with Module 03.
Find slow queries, read execution plans and speed them up with the right indexes and tuning techniques. Pairs with Module 04.
Script PostgreSQL backups with pg_dump, schedule them with cron and practice restoring from them. Pairs with Module 06.
Build a primary and replica pair with streaming replication to keep a live copy of your data. Pairs with Module 08.