DKIM, Dmarc, and spf configuration for a noob?

Finally had some time to sit down and read up /install open SSH on windows,
I checked the documentation about spf/dkim/dmarc, but didnt really understand how it would be implemented on a windows machine. the spf guide I had tried once earlier, but that made it so no mail at all was recieved(or send, it was a while ago now)

Anyhows.
I’m not comfortable sharing out my domain or public IP (self hosting, only using mail for private use)
lets call it testdomain.com
and say 10.11.12.13 as public IP.
The windows/mailserver is behind a pfsense firewall, only using webmail, and is setup to require being on the local network to use webmail (after seeing how horrendously many attemps to login every second when it was exposed to allow logins from internet)

/Peter