How to install Postgresql driver on WebLogic to create data source?

Question

PostgreSQL

I was trying to create my first data source in the Weblogic application server admin console. At the last step, when I click test configuration, it throws an error: Cannot load driver: org.postgresql.Driver. I tried to find a way to download a driver for it myself. I followed the instructions on this site
in cmd, I wrote the class path as follows as indicated on the oracle site in the setting class path section, that is:
set CLASSPATH= C:\Oracle\Middleware\Oracle_Home\wlserver\server\lib
set WEBLOGIC_CLASSPATH = C:\Oracle \Middleware\Oracle_Home\wlserver\server\lib
(I also read somewhere that it might be necessary to name the WEBLOGIC_CLASSPATH variable, so I wrote two)
it did not help, it still does not see the driver, the jar is still in the lib directory