first thing you need to address is does your isp allow it? Many will not, especially cable. You will get your broadband connection pulled--comcast is a devil on this and they constantly scan their network for listening port 80s
Even if they allow it, your bandwith may be insufficient. And I don't even want to address what happens if that version of windows server is pirated at it starts phoning home to MS....
Second, assuming the above is ok, is your IP address static or dynamic? If dynamic, that's an issue since a changing ip address makes hosting a website tricky at best, and problematic at worst.
Third you need public dns servers...
granite canyon offers the servicehttp://soa.granitecanyon.com/
It is slow at times, though...may be a better alternative, especially for UK users
you need to set up your ip address with your domain name so that traffic routes to you, if you intend to use your domain
After that, you just need to set up your server.
Seriously, though, this is not something you do lightly....anyone asking for a step by step for dummies probably shouldn't be hosting themselves. You can get a nice hosting package for every little money these days--including geekstogohttp://www.gtghosting.com/
(unintentional, intentional plug