Setup up a subdomain for my blog

There’s a great guide on how to set up a WordPress droplet on Digitalocean:

https://www.digitalocean.com/community/tutorials/how-to-use-the-wordpress-one-click-install-on-digitalocean-2

… but it stops short of indicating how to set up a subdomain that points to that WordPress instance.

What I’d like to do is set up a subdomain, blog.mydomain.com, which points to the home page (index.html) of that WordPress instance.

Yes, there’s an article on how to set up a subdomain to a domain, but it’s unclear what modifications (if any) to this process are required when working specifically with WordPress:

https://docs.digitalocean.com/products/networking/dns/how-to/add-subdomain/

Thanks for any help you can provide. And apologies in advance if this my question is already answered somewhere.