The Admin's Almanack
The OpenBSD FAQ and man pages are the final source of information for OpenBSD. You can also often search official project pages. For example, here are the project pages for relayd and OpenSMTPd.
Sample Config Files
Many system daemons that come bundled in OpenBSD base have sample configuration files that you can reference in /etc/examples/. For example, suppose you want to configure a web server. First, start with:
$ doas cp /etc/examples/httpd.conf /etc/httpd.conf
Then work using that configuration file as a template.
Take a look at any README files in /usr/local/share/doc/pkg-readmes/ . Often there are special configuration instructions to get a package to work properly on OpenBSD.
You can often find your questions answered by searching through the OpenBSD mailing lists, which are conveniently archived at marc.info. These are often answered by the OpenBSD developers themselves.
IRC Chat Room
You can find help in our unofficial OpenBSD IRC channel at . But before you ask a question, learn how to ask questions.