There are a lot of places to look at. https://www.postgresql.org/community/ is as good a place to start as any. Especially the mailing lists (yup, those things still exist) are very helpful. The mailing lists are pretty much the equivalent of PerlMonks in my opinion

If you need help semi-urgent or just want to hang out, #postgresql on irc.freenode.net is also a good place. Saved my bacon on a couple of occasions.

Last, but not least, if you need commercial PostgreSQL help for a big project, PostgreSQL got you covered: https://www.postgresql.org/support/professional_support/