DNScrypt is a protocol, not a resolver. It doesn't seem to be standardized. I suggest to start with the
Wikipedia page or
https://dnscrypt.info/ to find out how to use it.
How you configure your DNS server depends on your distro and its configuration. The traditional configuration file is /etc/resolv.conf; if your network parameters are set by DHCP, you need to ensure that you use the statically configured DNS server instead of the one transmitted by DHCP; and if you use systemd-resolved, you can configure it in /etc/systemd/resolved.conf.