Help with queries that pull data from two or more tables into powerBI via ODBC connection

Hi all

OK so I am new to ODBC connections and was super excited to get it to firstly work and then pull data from a table.  My ODBC connection uses a DSN from PostgreSQL.  I am new to sql statements, as in very new.  I can pull data from one table by doing the select * or selecting a few fields from one table but what I really need to do is pull data from 2 joined tables.  Can anyone show me a little example of how to do this in PowerBI (I pressume this is done in the ODBC, SQL advanced area)?  Basically if I have 2 tables table A and Table B which share a relationship via connection_id how do I do this?  Also filtering of results, is this done once the data is in powerBI via the filter options?

Any help for this excited newbie much appreciated.