Update PostgreSQL.md

updated with a few steps I had to search for when first setting up postgres

Author: the1gofer

docs/Containers/PostgreSQL.md

@@ -5,3 +5,10 @@
 ## About
 PostgreSQL is an SQL server, for those that need an SQL database. The database credentials can be found in the file `./volumes/postgres/postgres.env`. It is highly recommended to change the user, password and default database
 
+If you left the docker-compose.yml file with the default values, you can interact with the postgress in the container with the follwoing command, replacing `<<raspberypi ip>>` with the ip address to your RasperyPi.  
+`docker exec -it postgres psql -h <<raspberypi ip>> -d postdb -U postuser`
+
+Once you have logged in you should change the default password to postuser replacing `<<password>>` with your new password.
+`ALTER USER postuser WITH PASSWORD '<<password>>';`
+
+You can find more information about working with postgres at https://www.postgresql.org/docs/8.0/.