Creating a multisite

Is there an article on how to create multisites and add subdomains? I’ve started but I can’t find my .htaccess file to add that bit of code.
Additionally, when I am creating a local site I see the option to add as subdomain I believe.
Any and all help is appreciated. If even to point to an article or complete tutorial to get this done. I’ll keep searching in the meantime

I know this is an old post, but could help others too. i’m not sure if you have made it work. anyways, this is the site i followed when doing it:

doing it in local should be straight forward.