sounds like you have two queries here:
- how to use a Postgres data source in Qlik Sense
- how to administer Postgres
To use a postgres data source, you'll need to install the Postgres ODBC driver, then set up a System DSN in your ODBC connections. You should then be able to connect to your new ODBC connection in Qlik Sense.
To administer Postgres, there's a utility called PGAdmin, which is quite similar to SQL Server Management Studio.