Subdomain help

I’m wondering if y’all help (even with charge) moving things to a subdomain. I want things on my domain, yes, but since my website includes a personal and business aspect, I want a subdomain (I think) for the business aspect. I looked for a possible post that existed, in which I found this link

http://codex.wordpress.org/Giving_WordPress_Its_Own_Directory

and my brain died. I see too many terms I don’t know, so I need subdomain help with the ability to keep the theme on it. If that’s possible for y’all to help with.